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 A156657 #2 Mar 30 2012 18:51:04 %S A156657 0,1,2,3,4,6,8,9,10,12,13,14,15,16,17,18,19,20,21,22,24,25,26,27,28, %T A156657 29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,48,49,50,51,52, %U A156657 53,54,55,56,57,58,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77 %N A156657 Numbers that are not safe primes. %C A156657 A156659(a(n)) = 0; complement of A005385; A059456 is a subsequence; %C A156657 A010051(a(n))*A010051((a(n)-1)/2) = 0. %K A156657 nonn %O A156657 1,3 %A A156657 _Reinhard Zumkeller_, Feb 13 2009