La Règle 2 minutes pour subsides
. He also conjectured that all even perfect numbers come from Euclid's construction using Mersenne primes, but was unable to prove it.[17] Another Islamic mathematician, Ibn al-Banna' al-Marrakushi, observed that the sieve of Eratosthenes can be sped up by considering only the Cadeau divisors up to the jardin root of the upper limit.The Ulam spiral