300 (number) nontotient. 315 = 3 × 5 × 7. 315 is a Harshad number 316 = 2 × 79. 316 is a centered triangular number and a centered heptagonal number 317 is a prime number, Eisenstein prime with no imaginary part, Chen prime, and a strictly non-palindromic number. 317 is also shorthand for the LM317 adjustable regulator chip. It is also the area code for the Indianapolis region. 318 = 2 × 3 × 53. It is a sphenic number, nontotient, and the sum of twelve consecutive primes (7 + 11 + 13 + 17 + 19 + 23 + 29
Prime number prime and composite numbers. However, the earliest surviving records of the explicit study of prime numbers come from Ancient Greek mathematics. Euclid's "Elements" (circa 300 BC) proves the infinitude of primes and the fundamental theorem of arithmetic, and shows how to construct a perfect number from a Mersenne prime. Another Greek invention, the Sieve of Eratosthenes, is still used to construct lists of primes. Around 1000 AD, the Islamic mathematician Alhazen found Wilson's theorem, characterizing the prime numbers as the numbers formula_1 that evenly divide formula_17. Alhazen also conjectured that all even perfect numbers come from Euclid's construction using Mersenne