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 A335874 #26 Jul 05 2020 12:48:45 %S A335874 2,5,11,13,23,47,61,191,223,383,991,3583,3967,6143,16381,63487,253951, %T A335874 262111,786431,917503,1048447,1048573,4194271,14680063,16777183, %U A335874 67108351,260046847,3758096383,4261412863,51539607551,68718952447,266287972351,824633720831,1065151889407,1099503239167 %N A335874 Primes of the form q*2^h - 1, where q is a Mersenne prime (A000668). %C A335874 Primes p such that A331410(1+p) = 1. After 2, primes p for which A331410(p) = 2. %o A335874 (PARI) %o A335874 A000265(n) = (n>>valuation(n,2)); %o A335874 isA000668(n) = (isprime(n)&&!bitand(n,1+n)); %o A335874 isA335874(n) = (isprime(n)&&isA000668(A000265(1+n))); %Y A335874 Cf. A000040, A000265, A000668, A331410. %Y A335874 After 2, primes in A335882. %Y A335874 Cf. also A334092. %K A335874 nonn %O A335874 1,1 %A A335874 _Antti Karttunen_, Jun 28 2020 %E A335874 a(28)-a(35) from _David A. Corneth_, Jun 28 2020