import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.InputMismatchException;

/**
 * @author thesparkboy
 *
 */
public class A3 {

	static int n, MAX = (int) 1e5 + 1;
	static long memo[] = new long[MAX];

	static void sieve() {
		for (int i = 2; i < MAX; i++) {
			for (int j = 2 * i; j < MAX; j += i) {
				memo[j] += 4 * i;
			}
		}
	}

	public static void main(String[] args) {
		InputReader in = new InputReader(System.in);
		OutputWriter out = new OutputWriter(System.out);
		int t = 1;
		while (t-- > 0) {
			n = in.readInt();
			sieve();
			long sum = 0;
			while (n > 1) {
				sum += memo[n];
				n--;
			}
			System.out.println(sum);
		}
		out.close();
	}

	private static class InputReader {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public long readLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			long sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int readInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public String readString() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuffer res = new StringBuffer();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		static boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public String next() {
			return readString();
		}
	}

	private static class OutputWriter {
		private final PrintWriter writer;

		public OutputWriter(OutputStream outputStream) {
			writer = new PrintWriter(outputStream);
		}

		public OutputWriter(Writer writer) {
			this.writer = new PrintWriter(writer);
		}

		public void print(Object... objects) {
			for (int i = 0; i < objects.length; i++) {
				if (i != 0)
					writer.print(' ');
				writer.print(objects[i]);
			}
		}

		public void printLine(Object... objects) {
			print(objects);
			writer.println();
		}

		public void close() {
			writer.close();
		}
	}
}


import java.io.*;
import java.util.*;
import java.util.function.Function;

public class Main {

    static int N;

    public static void main(String[] args) {
        FastScanner sc = new FastScanner(System.in);
        N = sc.nextInt();

        System.out.println(solve());
    }

    static long solve() {
        long ans = 0;
        for (int i = 2; i <= N; i++) {
            int j = i + i;
            while(j <= N) {
                // debug(i, j);
                ans += j / i * 4;
                j += i;
            }
        }
        return ans;
    }

    static class Eratos {

        static int[] mkSqrtPrimes(long n) {
            long root_L = (long)Math.sqrt(n);
            if( root_L > 10_000_000 ) throw new IllegalArgumentException("too big : " + n);
            int root = (int)root_L;
            boolean[] sieve = new boolean[root+1];
            Arrays.fill(sieve, true);
            sieve[0] = false;
            sieve[1] = false;

            for (int i = 2; i <= root; i++) {
                if( sieve[i] ) {
                    for (int d = 2; d*i <= root; d++) {
                        sieve[i*d] = false;
                    }
                }
            }

            int cnt = 0;
            for (boolean prime : sieve) {
                if( prime ) cnt++;
            }
            int[] primes = new int[cnt];
            int idx = 0;
            for (int num = 2; num < sieve.length; num++) {
                if( sieve[num] ) {
                    primes[idx++] = num;
                }
            }
            return primes;
        }

        static int factorSize(long n) {
            // 6: 2 * 3 * 5 * 7 * 11 * 13 = 30030
            // 7: 2 * 3 * 5 * 7 * 11 * 13 * 17 = 510510
            // 8: 2 * 3 * 5 * 7 * 11 * 13 * 17 * 19 = 9699690
            // 9: 2 * 3 * 5 * 7 * 11 * 13 * 17 * 19 * 23 = 223_092_870
            // 10: 2 * 3 * 5 * 7 * 11 * 13 * 17 * 19 * 23 * 29 = 6_469_693_230
            // 11: 2 * 3 * 5 * 7 * 11 * 13 * 17 * 19 * 23 * 29 * 31 = 200_560_490_130
            if( n <= 2*3*5*7*11*13 ) {
                return 6;
            } else if( n <= 2*3*5*7*11*13*17 ) {
                return 7;
            } else if( n <= 2L*3*5*7*11*13*17*19 ) {
                return 8;
            } else if( n <= 2L*3*5*7*11*13*17*19*23 ) {
                return 9;
            } else if( n <= 2L*3*5*7*11*13*17*19*23*29 ) {
                return 10;
            } else if( n <= 2L*3*5*7*11*13*17*19*23*29*31 ) {
                return 11;
            } else {
                return 12;
            }
        }

        long n;
        int[] sqrtPrimes;
        int factorSize;

        // cache
        long[] factors;
        long[][] factorCnts;

        Eratos(long n) {
            this.n = n;
            this.sqrtPrimes = mkSqrtPrimes(n);
            this.factorSize = factorSize(n);
            this.factors = new long[this.factorSize];
            this.factorCnts = new long[this.factorSize][2];
        }

        long[] enumUniqFactors(long n) {
            Arrays.fill(factors, 0);
            int i = 0;
            for (int p : sqrtPrimes) {
                if( n % p == 0 ) {
                    factors[i++] = p;
                    n /= p;
                    while( n % p == 0 ) {
                        n /= p;
                    }
                }
            }
            if( n != 1 ) {
                factors[i++] = n;
            }
            return Arrays.copyOf(factors, i);
        }

        long[][] enumFactorCounts(long n) {
            for (long[] fc : factorCnts) {
                fc[0] = 0;
                fc[1] = 0;
            }
            int i = 0;
            for (int p : sqrtPrimes) {
                if( n < p ) break;

                int cnt = 0;
                while( n % p == 0 ) {
                    n/=p;
                    cnt++;
                }
                if( cnt > 0 ) {
                    factorCnts[i][0] = p;
                    factorCnts[i][1] = cnt;
                    i++;
                }
            }
            if( n != 1 ) {
                factorCnts[i][0] = n;
                factorCnts[i][1] = 1;
                i++;
            }
            return Arrays.copyOf(factorCnts, i);
        }

        Map<Long, Integer> mapFactorCounts(long n) {
            long[][] arr = enumFactorCounts(n);
            Map<Long, Integer> map = new HashMap<>();
            for (long[] fc : arr) {
                map.put(fc[0], (int)fc[1]);
            }
            return map;
        }
    }

    @SuppressWarnings("unused")
    static class FastScanner {
        private BufferedReader reader;
        private StringTokenizer tokenizer;

        FastScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken("\n");
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        int[] nextIntArray(int n, int delta) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt() + delta;
            return a;
        }

        long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }
    }

    static <A> void writeLines(A[] as, Function<A, String> f) {
        PrintWriter pw = new PrintWriter(System.out);
        for (A a : as) {
            pw.println(f.apply(a));
        }
        pw.flush();
    }

    static void writeLines(int[] as) {
        PrintWriter pw = new PrintWriter(System.out);
        for (int a : as) pw.println(a);
        pw.flush();
    }

    static void writeLines(long[] as) {
        PrintWriter pw = new PrintWriter(System.out);
        for (long a : as) pw.println(a);
        pw.flush();
    }

    static int max(int... as) {
        int max = Integer.MIN_VALUE;
        for (int a : as) max = Math.max(a, max);
        return max;
    }

    static int min(int... as) {
        int min = Integer.MAX_VALUE;
        for (int a : as) min = Math.min(a, min);
        return min;
    }

    static void debug(Object... args) {
        StringJoiner j = new StringJoiner(" ");
        for (Object arg : args) {
            if (arg instanceof int[]) j.add(Arrays.toString((int[]) arg));
            else if (arg instanceof long[]) j.add(Arrays.toString((long[]) arg));
            else if (arg instanceof double[]) j.add(Arrays.toString((double[]) arg));
            else if (arg instanceof Object[]) j.add(Arrays.toString((Object[]) arg));
            else j.add(arg.toString());
        }
        System.err.println(j.toString());
    }
}


import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Vadim
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastScanner in = new FastScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        R520_D solver = new R520_D();
        solver.solve(1, in, out);
        out.close();
    }

    static class R520_D {
        public void solve(int testNumber, FastScanner in, PrintWriter out) {
            int n = in.ni();
            long ans = 0;
            for (int i = 2; i < n; i++) {
                for (int j = i * 2; j <= n; j += i) {
                    //System.out.printf("%d %d %d%n",i,j,(j/i)*4);
                    ans += (j / i) * 4;
                }
            }
            out.println(ans);
        }

    }

    static class FastScanner {
        private BufferedReader in;
        private StringTokenizer st;

        public FastScanner(InputStream stream) {
            in = new BufferedReader(new InputStreamReader(stream));
        }

        public String ns() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    String rl = in.readLine();
                    if (rl == null) {
                        return null;
                    }
                    st = new StringTokenizer(rl);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

        public int ni() {
            return Integer.parseInt(ns());
        }

    }
}


import java.util.Scanner;

/**
 * @author yueqiuhong
 * @date 2020/10/17
 */
public class Main {

    static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        int n = in.nextInt();
        long sum = 0;
        for (int i = 2; i <= n; i++) {
            for (int j = i + i, k = 8; j <= n; j += i, k += 4) {
                sum += k;
            }
        }
        System.out.println(sum);
    }

}


import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the sockMerchant function below.

    private static final Scanner scanner = new Scanner(System.in);

    private static long sum(int n){
        return n * (n + 1) / 2 - 1;
    }

    public static void main(String[] args) throws IOException {
        long ans = 0;
        int n = scanner.nextInt();
        for(int i = 2; i < n; i++){
            if(n / i > 1)ans += sum(n / i);
        }
        System.out.println(4 * ans);
    }
}


import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the sockMerchant function below.

    private static final Scanner scanner = new Scanner(System.in);

    private static long sum(long n){
        return n * (n + 1) / 2 - 1;
    }

    public static void main(String[] args) throws IOException {
        long ans = 0;
        int n = scanner.nextInt();
        for(int i = 2; i < n; i++){
            if(n / i > 1)ans += sum(n / i);
        }
        System.out.println(4 * ans);
    }
}


import java.util.Scanner;

/**
 * @author leqiuhong@xiaomi.com
 * @date 2020/10/17
 */
public class Main {

    static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        int n = in.nextInt();
        long sum = 0;
        for (int i = 2; i <= n; i++) {
            for (int j = i + i, k = 8; j <= n; j += i, k += 4) {
                sum += k;
            }
        }
        System.out.println(sum);
    }

}


import java.io.*;
import java.util.*;

public class Codeforces1062D {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(System.out);
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());

		if (n <= 3) {
			System.out.println(0);
		}
		else {
			long ans = 0;
			for (int i = 2; i <= n; i++) {
				for (int j = 2; j <= (n/i); j++) {
					ans += (long) (4*j);
				}
			}
			System.out.println(ans);
		}
	}

}


import java.util.Scanner;

public class D {
    public static void main(String[] aaaa) {
        Scanner scanner = new Scanner(System.in);

        /*int[] prime = new int[1000005];

        for (int i = 2; i * i < prime.length; i++) {
            for (int j = i; j * i < prime.length; j++) {
                prime[j * i] = 1;
            }
        }
        */

        int _ = scanner.nextInt();
        long ans = 0;
        //base
        for (int i = 2; i < _; i++) {
            //start
            for (int j = 2; j * i <= _; j++) {
                //if (i % 2 == 0 || j % 2 == 0) {
                    //int tmp = i * ((int) (Math.log(_ / j) / Math.log(i) + 0.000001));
                    int tmp = i;

                    //System.out.println(i + " " + j);
                    //System.out.println(tmp);
                    ans += 4 * tmp;
                //}
            }
        }
        System.out.println(ans);
    }
}


import java.util.Scanner;

public class D {
    public static void main(String[] aaaa) {
        Scanner scanner = new Scanner(System.in);

        /*int[] prime = new int[1000005];

        for (int i = 2; i * i < prime.length; i++) {
            for (int j = i; j * i < prime.length; j++) {
                prime[j * i] = 1;
            }
        }
        */

        int _ = scanner.nextInt();
        long ans = 0;
        //base
        for (int i = 2; i < _; i++) {
            //start
            for (int j = 2; j * i <= _; j++) {
                int tmp = i * ((int)(Math.log(_ / j) / Math.log(i) + 0.000001));
                //System.out.println(i + " " + j);
                //System.out.println(tmp);
                ans += 4 * tmp;
            }
        }
        System.out.println(ans);
    }
}


import java.util.*;
import java.io.*;
import java.math.*;
/*
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(br.readLine());
Integer.parseInt(st.nextToken());
Long.parseLong(st.nextToken());
Scanner sc = new Scanner(System.in);

*/

public class Waw{

    public static long countDivisors(int n){
        long nb = 0;
        for(int i=2;i<=Math.sqrt(n);i++){
            if(n%i==0){
                if(n/i==i) nb += (long) (i*4);
                else{
                    nb += (long) (i*4);
                    nb += (long) ((n/i)*4);
                }
            }
        }

        return nb;
    }

    public static void main(String[] args){

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long nb = 0;
        for(int i=n;i>=2;i--){
            nb += countDivisors(i);
        }

        System.out.println(nb);

    }
}


import java.util.*;
import java.io.*;
public class Main implements Runnable{
    FastScanner sc;
    PrintWriter pw;
    final class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            try {
                br = new BufferedReader(new InputStreamReader(System.in));
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        public long nlo() {
            return Long.parseLong(next());
        }

        public String next() {
            if (st.hasMoreTokens()) return st.nextToken();
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
            return st.nextToken();
        }

        public int ni() {
            return Integer.parseInt(next());
        }

        public String nli() {
            String line = "";
            if (st.hasMoreTokens()) line = st.nextToken();
            else try {
                return br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            while (st.hasMoreTokens()) line += " " + st.nextToken();
            return line;
        }

        public double nd() {
            return Double.parseDouble(next());
        }
    }
    public static void main(String[] args)
    {
        new Thread(null,new Main(),"codeforces",1<<25).start();
    }
    public void run()
    {
        sc=new FastScanner();
        pw=new PrintWriter(System.out);
        solve();
        pw.flush();
        pw.close();
    }
    public void solve()
    {
        long n=sc.nlo();
        long ans=0;
        for(long x=2L;x<n;x++)
        {
            long y=n/x;
            ans+=(y*(y+1L)/2L);ans-=1L;
        }
        ans*=4L;
        pw.println(ans);
    }
}


import java.util.*;
import java.io.*;
public class Main implements Runnable{
    FastScanner sc;
    PrintWriter pw;
    final class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            try {
                br = new BufferedReader(new InputStreamReader(System.in));
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        public long nlo() {
            return Long.parseLong(next());
        }

        public String next() {
            if (st.hasMoreTokens()) return st.nextToken();
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
            return st.nextToken();
        }

        public int ni() {
            return Integer.parseInt(next());
        }

        public String nli() {
            String line = "";
            if (st.hasMoreTokens()) line = st.nextToken();
            else try {
                return br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            while (st.hasMoreTokens()) line += " " + st.nextToken();
            return line;
        }

        public double nd() {
            return Double.parseDouble(next());
        }
    }
    public static void main(String[] args)
    {
        new Thread(null,new Main(),"codeforces",1<<25).start();
    }
    public void run()
    {
        sc=new FastScanner();
        pw=new PrintWriter(System.out);
        solve();
        pw.flush();
        pw.close();
    }
    public void solve()
    {
        long n=sc.nlo();
        long ans=0;
        for(long x=2L;x<n;x++)
        {
           for(long j=x*2L;j<=n;j+=x)
           {
               ans+=j/x;
           }
        }
        ans*=4L;
        pw.println(ans);
    }
}


import java.io.*;
import java.util.*;

public class Main implements Runnable {
	FastReader scn;
	PrintWriter out;
	String INPUT = "";

	void solve() {
		int n = scn.nextInt();
		long ans = 0;
		for(int i = 2; i <= n; i++) {
			int x = 0;
			for(int j = 2 * i; j <= n; j += i) {
				x += j / i;
			}
			x *= 4;
			ans += x;
		}
		out.println(ans);
	}

	public void run() {
		long time = System.currentTimeMillis();
		boolean oj = System.getProperty("ONLINE_JUDGE") != null;
		out = new PrintWriter(System.out);
		scn = new FastReader(oj);
		solve();
		out.flush();
		if (!oj) {
			System.out.println(Arrays.deepToString(new Object[] { System.currentTimeMillis() - time + " ms" }));
		}
	}

	public static void main(String[] args) {
		new Thread(null, new Main(), "Main", 1 << 26).start();
	}

	class FastReader {
		InputStream is;

		public FastReader(boolean onlineJudge) {
			is = onlineJudge ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		}

		byte[] inbuf = new byte[1024];
		public int lenbuf = 0, ptrbuf = 0;

		int readByte() {
			if (lenbuf == -1)
				throw new InputMismatchException();
			if (ptrbuf >= lenbuf) {
				ptrbuf = 0;
				try {
					lenbuf = is.read(inbuf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return -1;
			}
			return inbuf[ptrbuf++];
		}

		boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		int skip() {
			int b;
			while ((b = readByte()) != -1 && isSpaceChar(b))
				;
			return b;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		char nextChar() {
			return (char) skip();
		}

		String next() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		String nextLine() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while ((!isSpaceChar(b) || b == ' ')) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		char[] next(int n) {
			char[] buf = new char[n];
			int b = skip(), p = 0;
			while (p < n && !(isSpaceChar(b))) {
				buf[p++] = (char) b;
				b = readByte();
			}
			return n == p ? buf : Arrays.copyOf(buf, p);
		}

		int nextInt() {
			int num = 0, b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		long nextLong() {
			long num = 0;
			int b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		char[][] nextMatrix(int n, int m) {
			char[][] map = new char[n][];
			for (int i = 0; i < n; i++)
				map[i] = next(m);
			return map;
		}

		int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		int[][] next2DInt(int n, int m) {
			int[][] arr = new int[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextIntArray(m);
			}
			return arr;
		}

		long[][] next2DLong(int n, int m) {
			long[][] arr = new long[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLongArray(m);
			}
			return arr;
		}

		int[] shuffle(int[] arr) {
			Random r = new Random();
			for (int i = 1, j; i < arr.length; i++) {
				j = r.nextInt(i);
				arr[i] = arr[i] ^ arr[j];
				arr[j] = arr[i] ^ arr[j];
				arr[i] = arr[i] ^ arr[j];
			}
			return arr;
		}

		int[] uniq(int[] arr) {
			Arrays.sort(arr);
			int[] rv = new int[arr.length];
			int pos = 0;
			rv[pos++] = arr[0];
			for (int i = 1; i < arr.length; i++) {
				if (arr[i] != arr[i - 1]) {
					rv[pos++] = arr[i];
				}
			}
			return Arrays.copyOf(rv, pos);
		}
	}
}


import java.io.*;
import java.util.*;

public class Main implements Runnable {
	FastReader scn;
	PrintWriter out;
	String INPUT = "";

	void solve() {
		int n = scn.nextInt();
		long ans = 0;
		for(int i = 2; i <= n; i++) {
			long x = 0;
			for(int j = 2 * i; j <= n; j += i) {
				x += j / i;
			}
			x *= 4;
			ans += x;
		}
		out.println(ans);
	}

	public void run() {
		long time = System.currentTimeMillis();
		boolean oj = System.getProperty("ONLINE_JUDGE") != null;
		out = new PrintWriter(System.out);
		scn = new FastReader(oj);
		solve();
		out.flush();
		if (!oj) {
			System.out.println(Arrays.deepToString(new Object[] { System.currentTimeMillis() - time + " ms" }));
		}
	}

	public static void main(String[] args) {
		new Thread(null, new Main(), "Main", 1 << 26).start();
	}

	class FastReader {
		InputStream is;

		public FastReader(boolean onlineJudge) {
			is = onlineJudge ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		}

		byte[] inbuf = new byte[1024];
		public int lenbuf = 0, ptrbuf = 0;

		int readByte() {
			if (lenbuf == -1)
				throw new InputMismatchException();
			if (ptrbuf >= lenbuf) {
				ptrbuf = 0;
				try {
					lenbuf = is.read(inbuf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return -1;
			}
			return inbuf[ptrbuf++];
		}

		boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		int skip() {
			int b;
			while ((b = readByte()) != -1 && isSpaceChar(b))
				;
			return b;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		char nextChar() {
			return (char) skip();
		}

		String next() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		String nextLine() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while ((!isSpaceChar(b) || b == ' ')) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		char[] next(int n) {
			char[] buf = new char[n];
			int b = skip(), p = 0;
			while (p < n && !(isSpaceChar(b))) {
				buf[p++] = (char) b;
				b = readByte();
			}
			return n == p ? buf : Arrays.copyOf(buf, p);
		}

		int nextInt() {
			int num = 0, b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		long nextLong() {
			long num = 0;
			int b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		char[][] nextMatrix(int n, int m) {
			char[][] map = new char[n][];
			for (int i = 0; i < n; i++)
				map[i] = next(m);
			return map;
		}

		int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		int[][] next2DInt(int n, int m) {
			int[][] arr = new int[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextIntArray(m);
			}
			return arr;
		}

		long[][] next2DLong(int n, int m) {
			long[][] arr = new long[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLongArray(m);
			}
			return arr;
		}

		int[] shuffle(int[] arr) {
			Random r = new Random();
			for (int i = 1, j; i < arr.length; i++) {
				j = r.nextInt(i);
				arr[i] = arr[i] ^ arr[j];
				arr[j] = arr[i] ^ arr[j];
				arr[i] = arr[i] ^ arr[j];
			}
			return arr;
		}

		int[] uniq(int[] arr) {
			Arrays.sort(arr);
			int[] rv = new int[arr.length];
			int pos = 0;
			rv[pos++] = arr[0];
			for (int i = 1; i < arr.length; i++) {
				if (arr[i] != arr[i - 1]) {
					rv[pos++] = arr[i];
				}
			}
			return Arrays.copyOf(rv, pos);
		}
	}
}


import java.io.*;
import java.util.*;

public class Main implements Runnable {
	FastReader scn;
	PrintWriter out;
	String INPUT = "";

	void solve() {
		int n = scn.nextInt();
		long ans = 0;
		for(int i = 2; i <= n; i++) {
			for(int j = 2 * i; j <= n; j += i) {
				ans += 4 * (j / i);
			}
		}
		out.println(ans);
	}

	public void run() {
		long time = System.currentTimeMillis();
		boolean oj = System.getProperty("ONLINE_JUDGE") != null;
		out = new PrintWriter(System.out);
		scn = new FastReader(oj);
		solve();
		out.flush();
		if (!oj) {
			System.out.println(Arrays.deepToString(new Object[] { System.currentTimeMillis() - time + " ms" }));
		}
	}

	public static void main(String[] args) {
		new Thread(null, new Main(), "Main", 1 << 26).start();
	}

	class FastReader {
		InputStream is;

		public FastReader(boolean onlineJudge) {
			is = onlineJudge ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		}

		byte[] inbuf = new byte[1024];
		public int lenbuf = 0, ptrbuf = 0;

		int readByte() {
			if (lenbuf == -1)
				throw new InputMismatchException();
			if (ptrbuf >= lenbuf) {
				ptrbuf = 0;
				try {
					lenbuf = is.read(inbuf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return -1;
			}
			return inbuf[ptrbuf++];
		}

		boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		int skip() {
			int b;
			while ((b = readByte()) != -1 && isSpaceChar(b))
				;
			return b;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		char nextChar() {
			return (char) skip();
		}

		String next() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		String nextLine() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while ((!isSpaceChar(b) || b == ' ')) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		char[] next(int n) {
			char[] buf = new char[n];
			int b = skip(), p = 0;
			while (p < n && !(isSpaceChar(b))) {
				buf[p++] = (char) b;
				b = readByte();
			}
			return n == p ? buf : Arrays.copyOf(buf, p);
		}

		int nextInt() {
			int num = 0, b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		long nextLong() {
			long num = 0;
			int b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		char[][] nextMatrix(int n, int m) {
			char[][] map = new char[n][];
			for (int i = 0; i < n; i++)
				map[i] = next(m);
			return map;
		}

		int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		int[][] next2DInt(int n, int m) {
			int[][] arr = new int[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextIntArray(m);
			}
			return arr;
		}

		long[][] next2DLong(int n, int m) {
			long[][] arr = new long[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLongArray(m);
			}
			return arr;
		}

		int[] shuffle(int[] arr) {
			Random r = new Random();
			for (int i = 1, j; i < arr.length; i++) {
				j = r.nextInt(i);
				arr[i] = arr[i] ^ arr[j];
				arr[j] = arr[i] ^ arr[j];
				arr[i] = arr[i] ^ arr[j];
			}
			return arr;
		}

		int[] uniq(int[] arr) {
			Arrays.sort(arr);
			int[] rv = new int[arr.length];
			int pos = 0;
			rv[pos++] = arr[0];
			for (int i = 1; i < arr.length; i++) {
				if (arr[i] != arr[i - 1]) {
					rv[pos++] = arr[i];
				}
			}
			return Arrays.copyOf(rv, pos);
		}
	}
}


import java.io.*;
import java.util.*;

public class Main implements Runnable {
	FastReader scn;
	PrintWriter out;
	String INPUT = "";

	void solve() {
		int n = scn.nextInt();
		long ans = 0;
		for(int i = 2; i <= n; i++) {
			for(int j = 2 * i, k = 8; j <= n; j += i, k += 4) {
				ans += k;
			}
		}
		out.println(ans);
	}

	public void run() {
		long time = System.currentTimeMillis();
		boolean oj = System.getProperty("ONLINE_JUDGE") != null;
		out = new PrintWriter(System.out);
		scn = new FastReader(oj);
		solve();
		out.flush();
		if (!oj) {
			System.out.println(Arrays.deepToString(new Object[] { System.currentTimeMillis() - time + " ms" }));
		}
	}

	public static void main(String[] args) {
		new Thread(null, new Main(), "Main", 1 << 26).start();
	}

	class FastReader {
		InputStream is;

		public FastReader(boolean onlineJudge) {
			is = onlineJudge ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		}

		byte[] inbuf = new byte[1024];
		public int lenbuf = 0, ptrbuf = 0;

		int readByte() {
			if (lenbuf == -1)
				throw new InputMismatchException();
			if (ptrbuf >= lenbuf) {
				ptrbuf = 0;
				try {
					lenbuf = is.read(inbuf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return -1;
			}
			return inbuf[ptrbuf++];
		}

		boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		int skip() {
			int b;
			while ((b = readByte()) != -1 && isSpaceChar(b))
				;
			return b;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		char nextChar() {
			return (char) skip();
		}

		String next() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		String nextLine() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while ((!isSpaceChar(b) || b == ' ')) { // when nextLine, (isSpaceChar(b) && b != ' ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		char[] next(int n) {
			char[] buf = new char[n];
			int b = skip(), p = 0;
			while (p < n && !(isSpaceChar(b))) {
				buf[p++] = (char) b;
				b = readByte();
			}
			return n == p ? buf : Arrays.copyOf(buf, p);
		}

		int nextInt() {
			int num = 0, b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		long nextLong() {
			long num = 0;
			int b;
			boolean minus = false;
			while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
				;
			if (b == '-') {
				minus = true;
				b = readByte();
			}

			while (true) {
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
				b = readByte();
			}
		}

		char[][] nextMatrix(int n, int m) {
			char[][] map = new char[n][];
			for (int i = 0; i < n; i++)
				map[i] = next(m);
			return map;
		}

		int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		int[][] next2DInt(int n, int m) {
			int[][] arr = new int[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextIntArray(m);
			}
			return arr;
		}

		long[][] next2DLong(int n, int m) {
			long[][] arr = new long[n][];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLongArray(m);
			}
			return arr;
		}

		int[] shuffle(int[] arr) {
			Random r = new Random();
			for (int i = 1, j; i < arr.length; i++) {
				j = r.nextInt(i);
				arr[i] = arr[i] ^ arr[j];
				arr[j] = arr[i] ^ arr[j];
				arr[i] = arr[i] ^ arr[j];
			}
			return arr;
		}

		int[] uniq(int[] arr) {
			Arrays.sort(arr);
			int[] rv = new int[arr.length];
			int pos = 0;
			rv[pos++] = arr[0];
			for (int i = 1; i < arr.length; i++) {
				if (arr[i] != arr[i - 1]) {
					rv[pos++] = arr[i];
				}
			}
			return Arrays.copyOf(rv, pos);
		}
	}
}


import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Try
{

    static class InputReader {

		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;

		public InputReader(InputStream st) {
			this.stream = st;
		}

		public int read() {
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int ni() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nl() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nia(int n) {
			int a[] = new int[n];
			for (int i = 0; i < n; i++) {
				a[i] = ni();
			}
			return a;
		}

		public String rs() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

	}

    static long mod=1000000007;
    static BigInteger bigInteger = new BigInteger("1000000007");
    static int n = (int)1e6;
    static boolean[] prime;
    static ArrayList<Integer> as;
    static HashSet<Integer> hs;
    static void sieve() {
			Arrays.fill(prime	, true);
			prime[0] = prime[1] = false;
			for(int i = 2 ; i * i <= n ; ++i) {
				if(prime[i]) {
					for(int k = i * i; k< n ; k+=i) {
						prime[k] = false;
					}
				}
			}

		}
		static PrintWriter w = new PrintWriter(System.out);
 static char [][]sol;
 static int t2 = 0;
         static int t3 = 0;
    public static void main(String[] args)
    {

        InputReader sc = new InputReader(System.in);
        //PrintWriter w = new PrintWriter(System.out);

        prime  = new boolean[n + 1];
		sieve();
		prime[1] = false;

		/*
		as = new ArrayList<>();
		for(int i=2;i<=1000000;i++)
		{
		    if(prime[i])
		    as.add(i);
		}
		*/

       /*

	long a = sc.nl();

            BigInteger ans = new BigInteger("1");
            for (long i = 1; i < Math.sqrt(a); i++) {
                if (a % i == 0) {
                    if (a / i == i) {
                        ans = ans.multiply(BigInteger.valueOf(phi(i)));

                    } else {
                        ans = ans.multiply(BigInteger.valueOf(phi(i)));
                        ans = ans.multiply(BigInteger.valueOf(phi(a / i)));

                    }

                }
            }
            w.println(ans.mod(bigInteger));
            */

         // MergeSort ob = new MergeSort();
       // ob.sort(arr, 0, arr.length-1);

    // Student []st = new Student[x];
   // st[i] = new Student(i,d[i]);
     //Arrays.sort(st,(p,q)->p.diff-q.diff);

   long ans = 0;
   int x = sc.ni();
   for(int i=2;i<=x;i++)
   {
       for(int j=2;j*i <=x;j++)
       {
           ans += (long) (j*4);
       }
   }
  w.println(ans);

   w.close();

    }
 static int digit(long x)
 {
     int p = 0;
     while(x > 0)
     {
         x /= 10;
         p++;
     }
     return p;
 }

    public static String f(String a,int b){
        if(b==0)
           return "";
       else if(b==1)
            return a;
        else{
            if(b%2==0)
               return f(a,b/2)+f(a,b/2);
            else
                return a+f(a,b/2)+f(a,b/2);
        }

    }

     static class Student
    {

        int first;
        int sec;
        Student(int first,int sec)
        {
            this.first = first;
            this.sec = sec;

        }

    }

     public static long modMultiply(long one, long two) {

		return (one % mod * two % mod) % mod;
	}
    static long fx(int m)
    {
        long re = 0;
        for(int i=1;i<=m;i++)
        {
            re += (long) (i / gcd(i,m));
        }
        return re;
    }
     static long gcd(long a, long b)
    {
	 if (a == 0)
	  return b;

	return gcd(b%a, a);
    }

     static long phi(long nx)
    {
        // Initialize result as n
        double result = nx;

        // Consider all prime factors of n and for
        // every prime factor p, multiply result
        // with (1 - 1/p)
        for (int p = 0; as.get(p) * as.get(p) <= nx; ++p)
        {
            // Check if p is a prime factor.
            if (nx % as.get(p) == 0)
            {
                // If yes, then update n and result
                while (nx % as.get(p) == 0)
                    nx /= as.get(p);
                result *= (1.0 - (1.0 / (double) as.get(p)));
            }
        }

        // If n has a prime factor greater than sqrt(n)
        // (There can be at-most one such prime factor)
        if (nx > 1)
            result *= (1.0 - (1.0 / (double) nx));

        return (long)result;

        //return(phi((long)result,k-1));

    }

    public static void primeFactors(long n)
    {
        //hs = new HashSet<>();

        // Print the number of 2s that divide n
        long temp = n;
       //System.out.print(2 + " ");
            //n /= 2;

        // n must be odd at this point.  So we can
        // skip one element (Note i = i +2)
        for (int i = 2; (long)i *(long)i<= n; i++)
        {
            // While i divides n, print i and divide n
            if (n%i == 0)
            {

               // System.out.print(i + " ");

                hs.add(i);
                //n /= i;

            }

        }

        // This condition is to handle the case whien
        // n is a prime number greater than 2
        /*
        if (n >= 2 && n*n <= temp)
        {

            hs.add(n);
        }
        */

    }
    static int digitsum(int x)

    {

        int sum = 0;
        while(x > 0)
        {
            int temp = x % 10;
            sum += temp;
            x /= 10;
        }
        return sum;

    }
    static int countDivisors(int n)
    {
        int cnt = 0;
        for (int i = 1; i*i <=n; i++)
        {
             if (n % i == 0)
             {
                // If divisors are equal,
                // count only one
                if (n / i == i)
                   cnt++;

                else // Otherwise count both
                    cnt = cnt + 2;
             }
         }
        return cnt;
    }

    static boolean isprime(long n)
    {

    if(n == 2)
        return true;
    if(n == 3)
        return true;
    if(n % 2 == 0)
        return false;
    if(n % 3 == 0)
        return false;

    long i = 5;
   long w = 2;

    while(i * i <= n)
    {
        if(n % i == 0)
            return false;

        i += w;
        w = 6 - w;
    }

    return true;
    }

    static long log2(long value) {
    return Long.SIZE-Long.numberOfLeadingZeros(value);
}

  public static int lowerBound(int[] array, int length, int value) {
        int low = 0;
        int high = length-1;
        while (low < high) {
            final int mid = (low + high) / 2;
            if (value <= array[mid]) {
                high = mid;
            } else {
                low = mid + 1;
            }
        }
        return low;
  }
  public static int upperBound(int[] array, int length, int value) {
        int low = 0;
        int high = length-1;
        while (low < high) {
            final int mid = (low + high) / 2;
            if (value >= array[mid]) {
                low = mid + 1;
            } else {
                high = mid;
            }
        }
        return low;
    }

    static boolean binarysearch(int []arr,int p,int n)
    {
        //ArrayList<Integer> as = new ArrayList<>();
        //as.addAll(0,at);
        //Collections.sort(as);
        boolean re = false;
        int st = 0;
        int end = n-1;

        while(st <= end)
        {
            int mid = st + (end-st)/2;

            if(p > arr[mid])
            {
                st = mid+1;

            }
            else if(p < arr[mid])
            {
                end = mid-1;

            }
            else if(p == arr[mid])
            {

            re = true;
            break;
            }

        }
         return re;

    }

    /* Java program for Merge Sort */
static class MergeSort
{
    // Merges two subarrays of arr[].
    // First subarray is arr[l..m]
    // Second subarray is arr[m+1..r]
    void merge(int arr[], int l, int m, int r)
    {
        // Find sizes of two subarrays to be merged
        int n1 = m - l + 1;
        int n2 = r - m;

        /* Create temp arrays */
        int L[] = new int [n1];
        int R[] = new int [n2];

        /*Copy data to temp arrays*/
        for (int i=0; i<n1; ++i)
            L[i] = arr[l + i];
        for (int j=0; j<n2; ++j)
            R[j] = arr[m + 1+ j];

        /* Merge the temp arrays */

        // Initial indexes of first and second subarrays
        int i = 0, j = 0;

        // Initial index of merged subarry array
        int k = l;
        while (i < n1 && j < n2)
        {
            if (L[i] <= R[j])
            {
                arr[k] = L[i];
                i++;
            }
            else
            {
                arr[k] = R[j];
                j++;
            }
            k++;
        }

        /* Copy remaining elements of L[] if any */
        while (i < n1)
        {
            arr[k] = L[i];
            i++;
            k++;
        }

        /* Copy remaining elements of R[] if any */
        while (j < n2)
        {
            arr[k] = R[j];
            j++;
            k++;
        }
    }

    // Main function that sorts arr[l..r] using
    // merge()
    void sort(int arr[], int l, int r)
    {
        if (l < r)
        {
            // Find the middle point
            int m = (l+r)/2;

            // Sort first and second halves
            sort(arr, l, m);
            sort(arr , m+1, r);

            // Merge the sorted halves
            merge(arr, l, m, r);
        }
    }

    /* A utility function to print array of size n */

}

    public static int ip(String s){
		return Integer.parseInt(s);
	}
	 public static String ips(int s){
		return Integer.toString(s);
	}

}


import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author cunbidun
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DFunWithIntegers solver = new DFunWithIntegers();
        solver.solve(1, in, out);
        out.close();
    }

    static class DFunWithIntegers {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            long ans = 0;
            for (int i = 2; i <= n; i++) {
                for (int j = 2; j * i <= n; j++) {
                    ans += j;
                }
            }
            out.println(ans * 4);
        }

    }

    static class InputReader extends InputStream {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        private static boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

    }
}


import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        d1062 solver = new d1062();
        solver.solve(1, in, out);
        out.close();
    }

    static class d1062 {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            boolean[] used = new boolean[n + 1];
            long ans = 0;
            for (int i = 2; i <= n; i++) {
                for (int j = 2; j <= n; j++) {
                    long next = i;
                    next *= j;
                    if (next > n) break;
                    ans += j * 4;
                }
            }
            out.println(ans);
        }

    }

    static class InputReader {
        private BufferedReader reader;
        private StringTokenizer stt;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream));
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (IOException e) {
                return null;
            }
        }

        public String next() {
            while (stt == null || !stt.hasMoreTokens()) {
                stt = new StringTokenizer(nextLine());
            }
            return stt.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}


import java.io.*;
import java.util.*;
public class r520p4{
	public static void main(String args[])throws IOException{
		solve();
	}

	private static void solve(){
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		long ans = 0;
		for(int i=2; i<=n; i++){
			for(int j=i*2; j<=n; j+=i)
				ans += 4*(j/i);
		}

		System.out.println(ans);
	}
}


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main implements Runnable {
    public static void main (String args[]){
        new Thread(null, new Main(), "Main", 1 << 26).start();
//        new Main().run();
    }

    public void run() {
        MyScanner sc = new MyScanner();

        int n = sc.nextInt();
        long res = 0;
        if (n <= 3) {
            System.out.println(0);
            return;
        }

        for (int i = 2; i <= n; i++) {
            for (int j = i * 2; j <= n; j += i) {
                res += 4 * j / i;
            }
        }
        System.out.println(res);
    }
}

class MyScanner {
    BufferedReader br;
    StringTokenizer st;

    public MyScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String nextLine(){
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }

}


//package Div2_520;

import java.util.Scanner;

public class D {
    static int n;
    static int snm[][];

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        n = in.nextInt() + 1;
        marked = new long[n];
        snm = new int[n][2];
        for (int i = 0; i < n; i++) {
            snm[i][0] = i;
        }
        func();
        long mas[] = new long[n];
        for (int i = 2; i < n; i++) {
            mas[snm[i][0]] += marked[i];
        }
        long ans = 0;
        for (int i = 0; i < n; i++) {
            if (mas[i] > ans) ans = mas[i];
        }
        System.out.println(ans);
    }

    private static void func() {
        for (int i = 0; i < n; i++) {
            marked[i] = -1;
        }
        for (int i = 2; i < n; i++) {
            if (marked[i] == -1) {
                fu(i);
            }
        }
    }

    private static void fu(int x) {
        marked[x] = 0;
        for (long i = 2; i * x < n; i++) {
            marked[x] += 4 * i;
            int y = pred(x);
            int z = pred((int) i * x);
            if (y != z) {
                if (snm[y][1] == snm[z][1]) {
                    snm[y][1]++;
                    snm[z][0] = y;
                } else if (snm[y][1] > snm[z][1]) {
                    snm[z][0] = y;
                } else {
                    snm[y][0] = z;
                }
            }
        }
    }

    private static int pred(int l) {
        while (snm[l][0] != l) {
            l = snm[l][0];
        }
        return l;
    }

    static long marked[];

}


import java.io.*;
import java.util.*;

public class FunWithIntegers
{
    PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));

    public void go()
    {
        int n = in.nextInt();
        int count = 0;
        for (int i = 2; i <= n; i++)
        {
            for (int j = 2; j*i <= n; j++)
            {
                count += j;
            }
        }
        out.println(count*4);

        out.flush();
        in.close();
    }

    public static void main(String[] args)
    {
        new FunWithIntegers().go();
    }
}


import java.io.*;
import java.util.*;

public class FunWithIntegers
{
    PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));

    public void go()
    {
        int n = in.nextInt();
        long count = 0;
        for (int i = 2; i <= n; i++)
        {
            for (int j = 2; j*i <= n; j++)
            {
                count += j;
            }
        }
        out.println(count*4);

        out.flush();
        in.close();
    }

    public static void main(String[] args)
    {
        new FunWithIntegers().go();
    }
}


// Author @ BlackRise :) //
// Birla Institute of Technology, Mesra//
import java.io.*;
import java.util.*;

public class funWithIntegers {

    static void Blackrise() {                                                //The name Blackrise is my pen name... you can change the name according to your wish

        int n=ni();

        tsc();                                                               //calculates the starting time of execution

        long ar[]=new long[100005];
        for(int i=2;i<100005;i++)
            for(int j=i+i;j<100005;j+=i)
                ar[j]+=j/i;

            long ans=0;
            for(int i=2;i<=n;i++)ans+=ar[i];
            pl(4*ans);

        tec();                  //calculates the ending time of execution
        //pwt();                //prints the time taken to execute the program
    }

    /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    static Calendar ts, te;                                                  //For time calculation
    static int mod9 = (int) 1e9 + 7;
    static Lelo input = new Lelo(System.in);
    static PrintWriter pw = new PrintWriter(System.out, true);

    public static void main(String[] args) {                                 //threading has been used to increase the stack size.

        new Thread(null, null, "BlackRise", 1<<25)  //the last parameter is stack size which is desired,
        {
            public void run() {

                try {
                    Blackrise();
                } catch (Exception e) {
                    e.printStackTrace();
                    System.exit(1);
                }
            }
        }.start();
    }

    static class Lelo {                                              //Lelo class for fast input
        private InputStream ayega;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public Lelo(InputStream ayega) {
            this.ayega = ayega;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = ayega.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public String nextLine() {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    // functions to take input//
    static int ni() {
        return input.nextInt();
    }

    static long nl() {
        return input.nextLong();
    }

    static double nd() {
        return input.nextDouble();
    }

    static String ns() {
        return input.readString();
    }

    //functions to give output
    static void pl() {
        pw.println();
    }

    static void p(Object o) {
        pw.print(o + " ");
    }

    static void pws(Object o){
        pw.print(o+"");
    }

    static void pl(Object o) {
        pw.println(o);
    }

    static void tsc()                                          //calculates the starting time of execution
    {
        ts = Calendar.getInstance();
        ts.setTime(new Date());
    }

    static void tec()                                          //calculates the ending time of execution
    {
        te = Calendar.getInstance();
        te.setTime(new Date());
    }

    static void pwt()                                          //prints the time taken for execution
    {
        pw.printf("\nExecution time was :- %f s\n", (te.getTimeInMillis() - ts.getTimeInMillis()) / 1000.00);
    }
}


import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
        public static void main(String[] args) {
                InputStream inputStream = System.in;
                OutputStream outputStream = System.out;
                InputReader in = new InputReader(inputStream);
                PrintWriter out = new PrintWriter(outputStream);
                TaskD solver = new TaskD();
                solver.solve(1, in, out);
                out.close();
        }

        static class TaskD {
                public void solve(int testNumber, InputReader in, PrintWriter out) {
                        int n = in.i();
                        long ans = 0;
                        for (int i = 4; i <= n; i++) {
                                ans += findValue(i);
                        }
                        out.println(ans * 4);
                }

                private long findValue(int n) {
                        long ans = 0;
                        for (int i = 2; i * i <= n; i++) {
                                if (n % i == 0) {
                                        if (i * i == n) {
                                                ans += n / i;
                                        } else {
                                                ans += n / i;
                                                ans += i;
                                        }
                                }
                        }
                        return ans;
                }

        }

        static class InputReader {
                InputStream is;
                private byte[] inbuf = new byte[1024];
                public int lenbuf = 0;
                public int ptrbuf = 0;

                public InputReader(InputStream is) {
                        this.is = is;
                }

                private int readByte() {
                        if (lenbuf == -1) throw new InputMismatchException();
                        if (ptrbuf >= lenbuf) {
                                ptrbuf = 0;
                                try {
                                        lenbuf = is.read(inbuf);
                                } catch (IOException e) {
                                        throw new InputMismatchException();
                                }
                                if (lenbuf <= 0) return -1;
                        }
                        return inbuf[ptrbuf++];
                }

                public int i() {
                        int num = 0, b;
                        boolean minus = false;
                        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
                        if (b == '-') {
                                minus = true;
                                b = readByte();
                        }

                        while (true) {
                                if (b >= '0' && b <= '9') {
                                        num = num * 10 + (b - '0');
                                } else {
                                        return minus ? -num : num;
                                }
                                b = readByte();
                        }
                }

        }
}


import java.util.*;
import java.io.*;
import static java.lang.Math.*;
public class Main {
    static final long MOD = 1_000_000_007, INF = 1_000_000_000_000_000_000L;
    static final int INf = 1_000_000_000;
    static FastReader reader;
    static PrintWriter writer;
    public static void main(String[] args) {
        Thread t = new Thread(null, new O(), "Integer.MAX_VALUE", 100000000);
        t.start();
    }
    static class O implements Runnable {
        public void run() {
            try {
                magic();
            }
            catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
    }
    public static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine(){
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

    }
    //variables here
    static void magic() {
        reader = new FastReader();
        writer = new PrintWriter(System.out, true);
        int n = reader.nextInt();
        long ans = 0;
        int np[] = new int[n+1];
        for(int i=2;i<=n;++i) {
            if(np[i]==0) {
                long sum = 0;
                for(int j=2*i;j<=n;j+=i) {
                    sum+=(j/i);
                    np[j]++;
                }
                sum*=2;
                ans+=sum;
            }
        }
        writer.println(ans*2);
    }
}


import java.util.*;
import java.io.*;
import static java.lang.Math.*;
public class Main {
    static final long MOD = 1_000_000_007, INF = 1_000_000_000_000_000_000L;
    static final int INf = 1_000_000_000;
    static FastReader reader;
    static PrintWriter writer;
    public static void main(String[] args) {
        Thread t = new Thread(null, new O(), "Integer.MAX_VALUE", 100000000);
        t.start();
    }
    static class O implements Runnable {
        public void run() {
            try {
                magic();
            }
            catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
    }
    public static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine(){
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

    }
    //variables here
    static void magic() {
        reader = new FastReader();
        writer = new PrintWriter(System.out, true);
        int n = reader.nextInt();
        long ans = 0;
        int np[] = new int[n+1];
        for(int i=2;i<=n;++i) {
            if(true) {
                long sum = 0;
                for(int j=2*i;j<=n;j+=i) {
                    sum+=(j/i);
                    np[j]++;
                }
                sum*=2;
                ans+=sum;
            }
        }
        writer.println(ans*2);
    }
}


import java.awt.List;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.TreeSet;

public final class CF_520_D2_D {

	static boolean verb=true;
	static void log(Object X){if (verb) System.err.println(X);}
	static void log(Object[] X){if (verb) {for (Object U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X){if (verb) {for (int U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X,int L){if (verb) {for (int i=0;i<L;i++) System.err.print(X[i]+" ");System.err.println("");}}
	static void log(long[] X){if (verb) {for (long U:X) System.err.print(U+" ");System.err.println("");}}

	static void logWln(Object X){if (verb) System.err.print(X);}
	static void info(Object o){	System.out.println(o);}
	static void output(Object o){outputWln(""+o+"\n");	}
	static void outputWln(Object o){try {out.write(""+ o);} catch (Exception e) {}}

	// Global vars
	static BufferedWriter out;
	static InputReader reader;

	static long mod=1000000007;

	static void process() throws Exception {

		out = new BufferedWriter(new OutputStreamWriter(System.out));
		reader=new InputReader(System.in);

		int n=reader.readInt();
		n++;
		int[] mem=new int[n];
		int[] cnt=new int[n];
		int tgt=-1;
		int max=0;

		int ext=0;
		long res=0;
		for (int i=2;i<n;i++){
			if (mem[i]==0){
				if (i*2>=n){
					// not able to explore
					ext=i;
				} else {
					int x=2*i;
					int sum=0;
					int diff=2;
					while (x<n){
						mem[x]=1;
						x+=i;
						sum+=diff;
						diff++;
					}
					log("i:"+i+" sum:"+sum);
					res+=sum;
				}
			} else {

			}
		}
		output(res*4);

		try {
			out.close();
		}
		catch (Exception EX){}

	}

	public static void main(String[] args) throws Exception {
		process();

	}

	static final class InputReader {
		private final InputStream stream;
		private final byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		private int read() throws IOException {
			if (curChar >= numChars) {
				curChar = 0;
				numChars = stream.read(buf);
				if (numChars <= 0) {
					return -1;
				}
			}
			return buf[curChar++];
		}

		public final String readString() throws IOException {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res=new StringBuilder();
			do {
				res.append((char)c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public final int readInt() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		public final long readLong() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	}

}


import java.awt.List;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.TreeSet;

public final class CF_520_D2_D {

	static boolean verb=true;
	static void log(Object X){if (verb) System.err.println(X);}
	static void log(Object[] X){if (verb) {for (Object U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X){if (verb) {for (int U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X,int L){if (verb) {for (int i=0;i<L;i++) System.err.print(X[i]+" ");System.err.println("");}}
	static void log(long[] X){if (verb) {for (long U:X) System.err.print(U+" ");System.err.println("");}}

	static void logWln(Object X){if (verb) System.err.print(X);}
	static void info(Object o){	System.out.println(o);}
	static void output(Object o){outputWln(""+o+"\n");	}
	static void outputWln(Object o){try {out.write(""+ o);} catch (Exception e) {}}

	// Global vars
	static BufferedWriter out;
	static InputReader reader;

	static long mod=1000000007;

	static void process() throws Exception {

		out = new BufferedWriter(new OutputStreamWriter(System.out));
		reader=new InputReader(System.in);

		int n=reader.readInt();
		n++;
		int[] mem=new int[n];
		int[] cnt=new int[n];
		int tgt=-1;
		int max=0;

		int ext=0;
		long res=0;
		for (int i=2;i<n;i++){
			if (mem[i]==0){
				if (i*2>=n){
					// not able to explore
					ext=i;
				} else {
					int x=2*i;
					long sum=0;
					long diff=2;
					while (x<n){
						mem[x]=i;
						x+=i;
						sum+=diff;
						diff++;
					}
					//log("i:"+i+" sum:"+sum);
					res+=sum;
				}
			} else {

			}
		}
		long ans=0;
		for (int u=2;u<n;u++){
			if (mem[u]!=0){
				for (int v=2;v*v<=u;v++){
					if (u%v==0){
						ans+=v;
						if (u!=v*v){
							ans+=u/v;
						}
					}
				}

			}
		}
		output(ans*4);
		//output(res*4);

		try {
			out.close();
		}
		catch (Exception EX){}

	}

	public static void main(String[] args) throws Exception {
		process();

	}

	static final class InputReader {
		private final InputStream stream;
		private final byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		private int read() throws IOException {
			if (curChar >= numChars) {
				curChar = 0;
				numChars = stream.read(buf);
				if (numChars <= 0) {
					return -1;
				}
			}
			return buf[curChar++];
		}

		public final String readString() throws IOException {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res=new StringBuilder();
			do {
				res.append((char)c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public final int readInt() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		public final long readLong() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	}

}


import java.awt.List;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.TreeSet;

public final class CF_520_D2_D {

	static boolean verb=true;
	static void log(Object X){if (verb) System.err.println(X);}
	static void log(Object[] X){if (verb) {for (Object U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X){if (verb) {for (int U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X,int L){if (verb) {for (int i=0;i<L;i++) System.err.print(X[i]+" ");System.err.println("");}}
	static void log(long[] X){if (verb) {for (long U:X) System.err.print(U+" ");System.err.println("");}}

	static void logWln(Object X){if (verb) System.err.print(X);}
	static void info(Object o){	System.out.println(o);}
	static void output(Object o){outputWln(""+o+"\n");	}
	static void outputWln(Object o){try {out.write(""+ o);} catch (Exception e) {}}

	// Global vars
	static BufferedWriter out;
	static InputReader reader;

	static long mod=1000000007;

	static void process() throws Exception {

		out = new BufferedWriter(new OutputStreamWriter(System.out));
		reader=new InputReader(System.in);

		int n=reader.readInt();
		n++;
		int[] mem=new int[n];
		int[] cnt=new int[n];
		int tgt=-1;
		int max=0;

		int ext=0;
		long res=0;
		for (int i=2;i<n;i++){
			if (mem[i]==0){
				if (i*2>=n){
					// not able to explore
					ext=i;
				} else {
					int x=2*i;
					long sum=0;
					long diff=2;
					while (x<n){
						mem[x]=1;
						x+=i;
						sum+=diff;
						diff++;
					}
					//log("i:"+i+" sum:"+sum);
					res+=sum;
				}
			} else {

			}
		}
		output(res*4);

		try {
			out.close();
		}
		catch (Exception EX){}

	}

	public static void main(String[] args) throws Exception {
		process();

	}

	static final class InputReader {
		private final InputStream stream;
		private final byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		private int read() throws IOException {
			if (curChar >= numChars) {
				curChar = 0;
				numChars = stream.read(buf);
				if (numChars <= 0) {
					return -1;
				}
			}
			return buf[curChar++];
		}

		public final String readString() throws IOException {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res=new StringBuilder();
			do {
				res.append((char)c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public final int readInt() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		public final long readLong() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	}

}


import java.util.*;
import java.io.*;
//import javafx.util.Pair;
public class Solution implements Runnable
{

    class Pair implements Comparable <Pair>
    {
        long x,y;
        Pair(long x,long y)
        {
            this.x=x;
            this.y=y;
        }
        public int compareTo(Pair p)
        {
            return Long.compare(x,p.x);
        }
    }

    public static void main(String[] args)
    {
        new Thread(null, new Solution(), "rev", 1 << 29).start();
    }

    public void run()
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(1,in,out);
        out.close();
    }

    class Task
    {

        long check(int n)
        {
            long sum=0;
            for(int i=2;i*i<=n;i++)
                if(n%i==0)
                {
                    if(i*i==n)
                        sum+=i;
                    else
                        sum+=(i+n/i);
                }
            return sum;
        }

        void solve(int testNumber, InputReader in, PrintWriter out)
        {
            int []a=new int[100001];
            for(int i=2;i*i<=100000;i++)
            {
                if(a[i]==0)
                    for(int j=2*i;j<=100000;j+=i)
                        a[j]=1;
            }
            long []ans=new long[100001];
            for(int i=2;i<=100000;i++)
                if(a[i]==1)
                    ans[i]=4*check(i);
            int n=in.nextInt();
            long sum=0;
            for(int i=2;i<=n;i++)
                sum+=ans[i];
            out.print(sum);
        }
    }

}
  class InputReader
{
    private InputStream stream;
    private byte[] buf = new byte[8192];
    private int curChar, snumChars;
    private SpaceCharFilter filter;

    public InputReader(InputStream stream)
    {
        this.stream = stream;
    }

    public int snext()
    {
        if(snumChars==-1)
            throw new InputMismatchException();
        if(curChar>=snumChars)
        {
            curChar=0;
            try
            {
                snumChars = stream.read(buf);
            }
            catch(IOException e)
            {
                throw new InputMismatchException();
            }
            if(snumChars<=0)
                return -1;
        }
        return buf[curChar++];
    }

    public int nextInt()
    {
        int c = snext();
        while(isSpaceChar(c))
            c=snext();
        int sgn=1;
        if(c=='-')
        {
            sgn = -1;
            c = snext();
        }
        int res=0;
        do
        {
            if(c<'0' || c>'9')
                throw new InputMismatchException();
            res*=10;
            res+=c-'0';
            c=snext();
            }while(!isSpaceChar(c));
        return res * sgn;
    }

    public long nextLong()
    {
        int c = snext();
        while(isSpaceChar(c))
            c=snext();
        int sgn=1;
        if(c=='-')
        {
            sgn=-1;
            c=snext();
        }
        long res=0;
        do{
            if (c<'0' || c>'9')
                throw new InputMismatchException();
            res*=10;
            res+=c-'0';
            c=snext();
        }while (!isSpaceChar(c));
        return res * sgn;
    }

    public int[] nextIntArray(int n)
    {
        int a[]=new int[n];
        for(int i=0; i<n; i++)
            a[i]=nextInt();
        return a;
    }

    public String nextString()
    {
        int c=snext();
        while(isSpaceChar(c))
            c=snext();
        StringBuilder res=new StringBuilder();
        do{
            res.appendCodePoint(c);
            c = snext();
        }while (!isSpaceChar(c));
        return res.toString();
    }

    public boolean isSpaceChar(int c)
    {
        if(filter != null)
            return filter.isSpaceChar(c);
        return c==' ' || c=='\n' || c=='\r' || c=='\t' || c==-1;
    }

    public interface SpaceCharFilter
    {
        public boolean isSpaceChar(int ch);
    }
}


import java.util.*;
import java.math.*;
import java.io.*;

public class CF1062D {
	// A Josh/Billy Collab (mostly Josh)
	final int MAX = 111111;
	public CF1062D() {
		Scanner scan = new Scanner(System.in);
		int n = Integer.parseInt(scan.next()); // ?
		long res = 0;
		for(int i = 2 ; i <= n ; i++) {
			Set<Integer> set = new HashSet<>();
			for(int j = 2 ; j * j <= n ; j++) {
				if(i % j == 0 && (i / j) != 1) {
					set.add(j);
					set.add(i / j);
				}
			}
			for(int x : set)
				res += 4 * (i / x);
		}
		System.out.println(res);
	}
	public static void main(String[] args) { new CF1062D(); }
}


import java.util.*;
import java.math.*;
import java.io.*;

public class CF1062D {
	// A Josh/Billy Collab (mostly Josh)
	final int MAX = 111111;
	public CF1062D() {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		List<Integer> primes = new ArrayList<>();
		boolean[] isPrime = new boolean[MAX];
		Arrays.fill(isPrime, true);
		isPrime[0] = isPrime[1] = false;
		for(int i = 2 ; i < MAX ; i++) {
			if(isPrime[i]) {
				primes.add(i);
				for(int j = i + i ; j < MAX ; j += i)
					isPrime[j] = false;
			}
		}
		long res = 0;
		boolean[] visited = new boolean[MAX];
		for(int prime : primes) {
			if(prime > n) break;
			if(prime <= n / 2 && prime != 2) res += 8;
			for(int i = prime * 2 ; i <= n ; i += prime) {
				if(visited[i]) continue;
				visited[i] = true;
				res += 4 * (i / prime);
			}
		}
		System.out.println(res);
	}
	public static void main(String[] args) { new CF1062D(); }
}


import java.util.Scanner;

public class d {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int N = in.nextInt();
		long L = 0;
		for(int i = 2; i <= N; i++) {
			for(int j = i+i; j <= N; j += i) {
				L += 4 * (j/i);
			}
		}
		System.out.println(L);
	}
}


import java.util.*;
import java.io.*;
import java.math.BigInteger;
import java.util.regex.*;

public class Codeforces{

	static class MyScanner{
		BufferedReader br;
		StringTokenizer st;

		MyScanner(FileReader fileReader){
			br = new BufferedReader(fileReader);
		}

		MyScanner(){
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String nn(){
			while(st == null || !st.hasMoreElements()){
				try{
					st = new StringTokenizer(br.readLine());
				}catch(IOException e){
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		String nextLine(){
			String s = "";
			try{
				s = br.readLine();
			}catch(IOException e){
				e.printStackTrace();
			}
			return s;
		}

		int ni(){
			return Integer.parseInt(nn());
		}

		long nl(){
			return Long.parseLong(nn());
		}

		double nd(){
			return Double.parseDouble(nn());
		}
	}

	private static PrintWriter out;

	public static void main(String[] args) throws FileNotFoundException{

		// Input from file
		// File inputFile = new File("JavaFile.txt");
		// File outputFile = new File("JavaOutputFile.txt");
		// FileReader fileReader = new FileReader(inputFile);
		// Here it ends

		MyScanner sc = new MyScanner();
		// MyScanner sc = new MyScanner(fileReader);

		out = new PrintWriter(new BufferedOutputStream(System.out)); // Output to console
		// out = new PrintWriter(new PrintStream(outputFile)); // Output to file

		int n = sc.ni();
		long ans = 0;

		for(int i = 2; i <= n; i++){
			ans += 4 * i * (n / i - 1);
		}

		out.println(ans);

		out.close();
	}
}


import java.util.Scanner;

public class Main {
    public static void main(String[] arg) {
        Scanner scanner = new Scanner(System.in);

        long n = scanner.nextInt();

        long res = 0;

        for(int i = 2; i <= n; i++){
            for(int mul = 2; mul <= Math.round(Math.sqrt(n)) + 1; mul++){
                if(i * mul <= n) res += 4 * mul;
            }
        }

        System.out.println(res);
    }
}


import java.util.Scanner;

public class Main {
    public static void main(String[] arg) {
        Scanner scanner = new Scanner(System.in);

        long n = scanner.nextInt();

        long res = 0;

        for(int i = 2; i <= n; i++){
            long count = n / i;
            res += 4 * (count*(count + 1) / 2 - 1);

        }

        System.out.println(res);
    }
}


import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.PrintStream;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Wolfgang Beyer
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskD solver = new TaskD();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskD {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            long score = 0;
            for (int x = 2; x <= n / 2; x++) {
                int c = n / x - 1;
//                System.out.println(i);
//                long x = 2 * (i + j) * (j - i + 1);
//                System.out.println(x);
                score += 4 * x * c;
            }
//        for (int i = 2; i <= n / 2; i++) {
//            if (n % i == 0) {
//                int j = n / i;
//                System.out.println(i);
//                long x = 2 * (i + j) * (j - i + 1);
//                System.out.println(x);
//                score += x;
//            }
//        }
            out.println(score);
        }

    }

    static class InputReader {
        private static BufferedReader in;
        private static StringTokenizer tok;

        public InputReader(InputStream in) {
            this.in = new BufferedReader(new InputStreamReader(in));
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public String next() {
            try {
                while (tok == null || !tok.hasMoreTokens()) {
                    tok = new StringTokenizer(in.readLine());
                    //tok = new StringTokenizer(in.readLine(), ", \t\n\r\f"); //adds commas as delimeter
                }
            } catch (IOException ex) {
                System.err.println("An IOException was caught :" + ex.getMessage());
            }
            return tok.nextToken();
        }

    }
}


import java.io.*;
import java.math.*;
import java.util.*;

public class D {

	public static void main(String[] args) throws NumberFormatException, IOException {
		Scanner sc = new Scanner(System.in);
		PrintWriter pw = new PrintWriter(System.out);
		int n = sc.nextInt();
		long ans = 0;
		for (int i = 2; i <= n; i++)
			for (int j = i * 2, k = 2; j <= n; j += i, k++) {
				ans += k * 4;
			}
		pw.println(ans);
		pw.flush();
	}

	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		public boolean ready() throws IOException {
			return br.ready();
		}
	}

}