A109317 Column 0 of triangle T=A109316 where T(n,k) = [T^2](n-1,k) + [T^2](n-2,k-1) and T^2 is the matrix square of T.

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

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)[i-1, j]+if(j>1, (A^2)[i-2, j-1]))); )); 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