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 A031994 #10 Aug 12 2015 08:26:52 %S A031994 0,1,2,3,4,5,6,7,8,10,11,12,13,14,15,16,17,20,21,22,23,24,25,26,30,31, %T A031994 32,33,34,35,40,41,42,43 %N A031994 Duplicate of A023751. %K A031994 dead %O A031994 1,3