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 A064308 #3 Mar 31 2012 13:20:06 %S A064308 1,4,2,13,20,5,41,149,98,14,131,1022,1330,462,42,428,6866,15768,9990, %T A064308 2112,132,1429,46188,176229,181170,66792,9438,429,4861,313601,1917960, %U A064308 3003990,1717287,411411,41470,1430 %N A064308 Product of two triangular matrices C*S2. %C A064308 This triangular matrix appears in the definition of the row polynomials for triangle A064307. %C A064308 The first column sequence (m=1) gives A001453(n+1). The main diagonal gives A000108(n+1). Row sums give A064309. %F A064308 a(n, m)=sum(A009766(n, k)*A008277(k, m), k=m..n), n >= m >= 1 else 0. Product of Catalan triangular matrix (without row n=0 and column m=0) with Stirling2 triangular matrix. %K A064308 nonn,easy,tabl %O A064308 1,2 %A A064308 _Wolfdieter Lang_, Sep 13 2001