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 A031975 #1 Dec 11 1999 03:00:00 %S A031975 1,2,3,5,6,7,8,10,11,11,13,14,15,16,17,19,21,22,23,24,26,27,29,30,31, %T A031975 33,34,35,37,38,39,41,42,43,45,47,48,50,53 %N A031975 Erroneous version of A000452. %K A031975 dead %O A031975 1,2