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 A095721 #3 Jan 09 2009 03:00:00 %S A095721 1,2,3,5,4,7,6,10,8,13,9,15,11,18,12,20,14,23,16,26,17,28,19,31,21,34 %N A095721 Duplicate of A072061. %K A095721 dead %O A095721 1,2