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 A058166 #6 Mar 30 2012 17:37:12 %S A058166 1,4,4,24,54,35,356,1044,1488,604,16585,31620,60900,57900,16727, %T A058166 3461916,1699290,3345420,4744380,3128880,681232,6058301508,265521354, %U A058166 263429355,439698420,455785470,222132666,38187291 %N A058166 Triangle read by rows: T(n,k) = number of labeled semigroups of order n with k idempotents. %H A058166 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a> %e A058166 1; 4,4; 24,54,35; 356,1044,1488,604; ... %Y A058166 Row sums give A023814. %K A058166 nonn,tabl,hard %O A058166 1,2 %A A058166 _Christian G. Bower_, Nov 15 2000