The conversation between human and AI assistant.
How many of the first 1200 natural numbers are either prime to 6 or to 15?
That's interesting. How do you compute the value of Euler's totient function for a given number?
We can use the formula φ(N) = N x ∏p|N (1 - 1/p), where p ranges over the distinct prime factors of N. For example, the prime factors of 6 are 2 and 3. Therefore, φ(6) = 6 x (1-1/2) x (1-1/3) = 2.