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 A031092 #4 Mar 30 2012 18:56:20 %S A031092 4,17,35,53,64,66,68,70,71,72,74,76,78,80,89,107,125,143,165,192,219, %T A031092 246,262,265,268,271,273,274,277,280,283,286,300,327,354,381,408,435, %U A031092 462,489,505,508,511,514,516,517,520,523,526 %N A031092 Position of n-th 4 in A031087. %K A031092 nonn %O A031092 1,1 %A A031092 _Clark Kimberling_