A121417 - OEIS

A121417

Column 1 of triangle A121416.

1, 2, 9, 69, 769, 11346, 208914, 4613976, 118840164, 3496297632, 115638728395, 4246267163601, 171369282105510, 7538270885559264, 358926669220446804, 18389706733665138450, 1008742283718489346668, 58981158542987625464424

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OFFSET

0,2

COMMENTS

Also column 1 of square array A136737.

A121416 is the matrix square of triangle A121412; row n of triangle T=A121412 equals row (n-1) of T^(n+1) with an appended '1'.

LINKS

Table of n, a(n) for n=0..17.

PROG

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

CROSSREFS

Cf. A121416 (triangle); other columns: A121418, A121419.

Cf. A136737; A121413, A121422; A121427, A136741.

Sequence in context: A319285 A316652 A330471 * A232549 A369778 A284762

Adjacent sequences: A121414 A121415 A121416 * A121418 A121419 A121420

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Aug 22 2006

EXTENSIONS

Edited by N. J. A. Sloane, Oct 30 2008 at the suggestion of R. J. Mathar

STATUS

approved