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 A191264 #5 Mar 30 2012 18:57:31 %S A191264 5,16,21,26,31,42,53,64,75,80,85,90,101,106,111,116,127,132,137,142, %T A191264 153,158,163,168,179,190,201,212,217,222,227,238,249,260,271,276,281, %U A191264 286,297,308,319,330,335,340,345,356,367,378,389,394,399,404,415,420,425,430,441,446,451,456,467,472,477,482,493,504 %N A191264 Positions of 2 in A191261. %C A191264 See A191261. %t A191264 (See A191261.) %Y A191264 Cf. A191261, A191250. %K A191264 nonn,easy %O A191264 1,1 %A A191264 _Clark Kimberling_, May 28 2011