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 A058117 #6 Mar 30 2012 17:37:11 %S A058117 1,2,5,16,62,342,3435 %N A058117 Number of commutative semigroups of order n with 1 idempotent. %H A058117 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a> %Y A058117 Column 1 of A058116. %K A058117 nonn,hard %O A058117 1,2 %A A058117 _Christian G. Bower_, Nov 09 2000