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 A031042 #4 Mar 30 2012 18:56:20 %S A031042 6,21,37,53,69,85,88,90,92,94,96,98,100,101,102,117,140,164,188,212, %T A031042 236,260,265,268,271,274,277,280,283,284,286,308,332,356,380,404,428, %U A031042 452,457,460,463,466,469,472,475,476,478,500,524 %N A031042 Position of n-th 6 in A031035. %K A031042 nonn %O A031042 1,1 %A A031042 _Clark Kimberling_