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 A058137 #7 May 22 2015 07:45:43 %S A058137 1,1,1,1,3,3,2,9,14,10,1,32,63,86,46,2,219,406,694,665,251,1,5585, %T A058137 3331,6343,8582,6035,1682,5 %N A058137 Triangle read by rows: monoids of order n with k idempotents. %H A058137 <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a> %e A058137 1; 1,1; 1,3,3; 2,9,14,10; 1,32,63,86,46; ... %Y A058137 Row sums give A058129. Main diagonal: A058112(n-1). Columns 1-3: A000001, A058138, A058139. %K A058137 nonn,tabl,more %O A058137 1,5 %A A058137 _Christian G. Bower_, Nov 14 2000