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 A143303 #23 Apr 24 2015 21:38:41 %S A143303 1,3,5,1,1,3,1,5,7,4,4,9,1,6,5,9,0,0,1,7,9,3,8,6,8,0,0,5,2,5,6,5,2,1 %N A143303 Duplicate of A074903. %K A143303 dead %O A143303 1,2