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 A191260 #5 Mar 30 2012 18:57:31 %S A191260 4,12,21,29,35,39,47,56,64,68,76,84,93,101,107,111,119,128,136,144, %T A191260 153,161,170,178,184,188,196,205,213,217,225,233,242,250,256,260,268, %U A191260 277,285,294,302,308,312,320,329,337,343,347,355,364,372,376,384,392,401,409,415,419,427,436,444,452,461,469,478,486,492,496,504 %N A191260 Positions of 2 in A191258. %C A191260 See A191258. %t A191260 (See A191258.) %Y A191260 Cf. A191258, A191250. %K A191260 nonn,easy %O A191260 1,1 %A A191260 _Clark Kimberling_, May 28 2011