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 A105557 #3 Mar 30 2012 18:36:45 %S A105557 1,2,4,10,32,128,626,3681,25574,206402,1908996,20024149,236142157, %T A105557 3106393358,45265833590,726249472784,12761749378320,244453274012442, %U A105557 5082582988294164,114258645210526486,2767462674168199303 %N A105557 Row sums of triangle A105556, in which column n equals the row sums of A001263^n, which is the n-th matrix power of the Narayana triangle A001263. %o A105557 (PARI) {a(n)=local(N=matrix(n+1,n+1,m,j,if(m>=j, binomial(m-1,j-1)*binomial(m,j-1)/j))); sum(k=0,n,sum(j=0,n-k,(N^k)[n-k+1,j+1]))} %Y A105557 Cf. A001263, A105556. %K A105557 nonn %O A105557 0,2 %A A105557 _Paul D. Hanna_, Apr 14 2005