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 A089921 #3 May 11 2007 03:00:00 %S A089921 2,3,11,83,227,443,1091,1523,2027,3251,6563,9803,11027,12323,13691 %N A089921 Duplicate of A056899. %K A089921 dead %O A089921 1,1