

A109317


Column 0 of triangle T=A109316 where T(n,k) = [T^2](n1,k) + [T^2](n2,k1) and T^2 is the matrix square of T.


3



1, 1, 2, 6, 22, 94, 446, 2294, 12542, 71974, 429342, 2643606, 16710382, 107980870, 710933118, 4756345750, 32265548622, 221540438502, 1537355395934, 10768777480374, 76063545106670, 541277072787334, 3877624448977150
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OFFSET

0,3


LINKS

Table of n, a(n) for n=0..22.


PROG

(PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, if(i==2, B[i, j]=1, B[i, j]=(A^2)[i1, j]+if(j>1, (A^2)[i2, j1]))); )); A=B); return(A[n+1, 1])}


CROSSREFS

Cf. A109316 (triangle), A109318 (column 1), A109319 (row sums), A000108.
Sequence in context: A185349 A317652 A150274 * A109153 A030453 A001861
Adjacent sequences: A109314 A109315 A109316 * A109318 A109319 A109320


KEYWORD

nonn


AUTHOR

Paul D. Hanna, Jul 07 2005


STATUS

approved



