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 A100991 #2 Nov 10 2007 03:00:00 %S A100991 0,1,3,4,7,8,9,11,12,13,16,17,19,21,23,24,25,27,28,29,31,32,33,36,37, %T A100991 39 %N A100991 Duplicate of A075821. %K A100991 dead %O A100991 1,3