A109318 Column 2 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 A109316.

1, 2, 8, 36, 176, 920, 5080, 29336, 175752, 1085496, 6877240, 44518520, 293513784, 1965904984, 13348449784, 91723622936, 636923476728, 4463989946072, 31545992160568, 224580029779608, 1609455072125816, 11603437881340888

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Prog

(PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+3, 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+3, 3])}

Crossrefs

Cf. A109316 (triangle), A109317 (column 0), A109319 (row sums), A000108.

Sequence in context: A110837 A372088 A166229 * A113327 A227791 A245102

Adjacent sequences: A109315 A109316 A109317 * A109319 A109320 A109321

Keyword

nonn

Author

Paul D. Hanna, Jul 07 2005

Status

approved