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 A058147 #6 Mar 30 2012 17:37:11 %S A058147 1,1,1,1,3,2,2,9,10,6,1,30,47,52,26,2,175,283,413,365,135,1,3333,2139, %T A058147 3630,4597,3155,875,5 %N A058147 Triangle read by rows: number of monoids of order n with k idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator). %H A058147 <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a> %e A058147 1; 1,1; 1,3,2; 2,9,10,6; 1,30,47,52,26; ... %Y A058147 Row sums give A058133. Main diagonal: A002788(n-1). Columns 1-3: A000001, A058148, A058149. %K A058147 nonn,tabl,more %O A058147 1,5 %A A058147 _Christian G. Bower_, Nov 14 2000