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 A031995 #4 Sep 29 2006 03:00:00 %S A031995 0,1,2,3,4,5,6,7,8,9,10,12,13,14,15,16,17,18,19,20,21,24,25,26,27,28 %N A031995 Duplicate of A023752. %K A031995 dead %O A031995 1,3