cp's OEIS Frontend

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.

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.

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%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