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 A031221 #4 Mar 30 2012 18:56:21 %S A031221 1,5,7,8,9,11,13,18,28,38,45,48,50,51,54,57,60,61,63,64,65,66,67,69, %T A031221 70,72,73,75,78,80,81,84,87,90,93,95,96,99,102,105,108,110,111,114, %U A031221 117,125,136,139,140,142,145,148,155,170,185,200 %N A031221 Position of n-th 1 in A031219. %K A031221 nonn %O A031221 1,2 %A A031221 _Clark Kimberling_