This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A218582 #9 Jun 23 2025 22:17:38 %S A218582 2,5,11,13,17,19,29,37,41,43,53,59,61,67,71,73,79,83,97,101,103,107, %T A218582 109,113,131,137,139,149,151,157,163,173,179,181,191,193,197,199,211, %U A218582 227,229,239,241,251,257,269,271,277,281,283,293,307,311,313,317,331,337 %N A218582 Primes which do not divide any Mersenne number M(p) = 2^p - 1 with prime p. %H A218582 Arkadiusz Wesolowski, <a href="/A218582/b218582.txt">Table of n, a(n) for n = 1..10000</a> %t A218582 Select[Prime@Range[68], ! PrimeQ@MultiplicativeOrder[2, #] &] %o A218582 (Magma) [p: p in PrimesInInterval(2, 337) | not IsPrime(Modorder(2, p))]; %Y A218582 Complement in primes of A122094. Subsequence of A138837. %K A218582 nonn %O A218582 1,1 %A A218582 _Arkadiusz Wesolowski_, Nov 03 2012