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 A058139 #5 Mar 30 2012 17:37:11 %S A058139 3,14,63,406,3331 %N A058139 Monoids of order n with 3 idempotents. %H A058139 <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a> %Y A058139 Column 3 of A058137. %K A058139 nonn,more %O A058139 3,1 %A A058139 _Christian G. Bower_, Nov 14 2000