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 A133200 #5 Feb 08 2022 19:37:07 %S A133200 1,1,2,1,6,2,1,12,12,2,1,20,40,20,2,1,30,100,100,30,2,1,42,210,350, %T A133200 210,42,2,1,56,392,980,980,392,56,2,1,72,672,2352,3528,2352,672,72,2, %U A133200 1,90,1080,5040,10584,10584,5040,1080,90,2 %N A133200 A001263 * A136521 as infinite lower triangular matrices, where A001263 = the Narayana triangle and A136521 = an infinite lower triangular matrix with (1, 2, 2, 2, ...) in the main diagonal and the rest zeros. %C A133200 Row sums = A131428 starting (1, 3, 9, 27, 83, 263, ...). %e A133200 First few rows of the triangle: %e A133200 1; %e A133200 1, 2; %e A133200 1, 6, 2; %e A133200 1, 12, 12, 2; %e A133200 1, 20, 40, 20, 2; %e A133200 1, 30, 100, 100, 30, 2; %e A133200 1, 42, 210, 350, 210, 42, 2; %e A133200 ... %Y A133200 Cf. A001263, A136521. %K A133200 nonn,tabl %O A133200 1,3 %A A133200 _Gary W. Adamson_, Jan 02 2008