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 A180924 #6 Dec 15 2017 17:37:11 %S A180924 4,24,29,47,61,63,67,69,87,101,129,143,153,249,252,333,408,561,616, %T A180924 732,929,1349,3467,6156,6919,9244,14413,17128,20059,20169,20512,23479, %U A180924 24076,26208,27189 %N A180924 Numbers n such that 12321*2^n + 1 is prime. %o A180924 (PARI) is(n)=ispseudoprime(12321<<n+1) \\ _Charles R Greathouse IV_, Jun 13 2017 %K A180924 nonn %O A180924 1,1 %A A180924 _Jason Earls_, Sep 25 2010