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 A031048 #4 Mar 30 2012 18:56:20 %S A031048 2,12,25,27,28,29,31,33,35,37,39,44,60,76,92,108,126,150,169,172,174, %T A031048 175,178,181,184,187,190,198,222,246,270,294,314,317,318,320,323,326, %U A031048 329,332,335,338,341,342,344,347,350,353,356 %N A031048 Position of n-th 2 in A031045. %K A031048 nonn %O A031048 1,1 %A A031048 _Clark Kimberling_