cp's OEIS Frontend

A set of primes is called the covering set for the Sierpiński number k if for every positive integer m there is at least one prime in the set which divides k*2^m + 1. Similarly, a set of primes is called the covering set for the Riesel number j if for every positive integer m there is at least one prime in the set which divides j*2^m - 1.

Let p be a prime number of the form 3*153479820268467961^2*2^k + 1 with k > 0, then the multiplicative order of 2 modulo p is not of the form 2^(m+1), m >= 0. Hence, p does not divide any Fermat number F(m) = 2^(2^m) + 1.