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 A031301 #4 Mar 30 2012 18:56:21 %S A031301 2,14,31,33,34,35,37,39,41,43,45,47,49,54,74,94,114,134,154,174,196, %T A031301 226,251,254,256,257,260,263,266,269,272,275,278,286,316,346,376,406, %U A031301 436,466,492,495,496,498,501,504,507,510,513,516 %N A031301 Position of n-th 2 in A031298. %K A031301 nonn %O A031301 1,1 %A A031301 _Clark Kimberling_