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 A135722 #6 Mar 27 2022 23:29:26 %S A135722 1,1,1,1,1,2,1,1,3,5,1,1,3,15,14,1,1,3,23,84,42,1,1,3,27,244,466,132, %T A135722 1,1,3,28,494,2444,2514,429,1,1,3,28,796,8720,22022,13233,1430,1,1,3, %U A135722 28,1094,24394,128514,181841,68376,4862 %N A135722 A000012 * A122890. %C A135722 Row sums = A003422: (1, 2, 4, 10, 34, 154, 874, ...). %C A135722 Main diagonal = A000108, the Catalan numbers: (1, 1, 2, 5, 14, 42, 132, ...). %F A135722 A000012 * A122890 as infinite lower triangular matrices. %e A135722 First few rows of the triangle: %e A135722 1; %e A135722 1, 1; %e A135722 1, 1, 2; %e A135722 1, 1, 3, 5; %e A135722 1, 1, 3, 15, 14; %e A135722 1, 1, 3, 23, 84, 42; %e A135722 1, 1, 3, 27, 244, 466, 132; %e A135722 1, 1, 3, 28, 494, 2444, 2514, 429; %e A135722 ... %Y A135722 Cf. A003422, A122890, A000108. %K A135722 nonn,tabl %O A135722 0,6 %A A135722 _Gary W. Adamson_, Nov 25 2007