Mersenne primes

来源: 于 2008-01-28 18:53:08 [旧帖] [给我悄悄话] 本文已被阅读：次

A Mersenne prime is a prime number of the form 2^n-1; for instance, 7 = 2^3-1.
Prove that if 2^n-1 is a prime then 2^n+1 is not a prime for n>2.
Is there a name for the primes of the form 2^n+1?