 Euclid's "Elements" (c. 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 Ibn al-Haytham (Alhazen) found Wilson's theorem, characterizing the prime numbers as the numbers formula_1 that evenly divide formula_17.