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 A058121 #6 Mar 30 2012 17:37:11 %S A058121 2,16,112,764,5567 %N A058121 Number of self-converse semigroups of order n with 3 idempotents. %H A058121 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a> %Y A058121 Column 3 of A058118. %K A058121 nonn,hard %O A058121 3,1 %A A058121 _Christian G. Bower_, Nov 10 2000