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A126467
Column 1 of triangle A126465.
4
1, 1, 6, 105, 3710, 219625, 19545316, 2437990653, 405899413380, 87002614878795, 23351252019790310, 7676367378822833691, 3035533054438876836390, 1422385798272704860377055, 779768824083518449340320720
OFFSET
0,3
PROG
(PARI) {a(n)=local(M=matrix(n+2, n+2, r, c, if(r>=c, binomial((r-1)*r*(r+1)/3!-(c-1)*c*(c+1)/3!, r-c))), N=matrix(n+2, n+2, r, c, if(r>=c, binomial((r-1)*r*(r+1)/3!-(c-1)*c*(c+1)/3!+1, r-c)))); (N*M^-1)[n+2, 2]}
CROSSREFS
Cf. A126465, A126466, A126468; A126469 (row sums).
Sequence in context: A221933 A110342 A227207 * A013294 A013300 A330769
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 27 2006
STATUS
approved