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A121422

Column 1 of triangle A121420.

1, 3, 15, 118, 1317, 19311, 352636, 7722840, 197354133, 5764942816, 189460961985, 6917588290044, 277765971072770, 12163275845132298, 576793897136731632, 29444368084753254610, 1609805318425385690712, 93843785859803533422675

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OFFSET

0,2

COMMENTS

Also column 2 of square array A136737.

A121420 is the matrix cube 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^3)[n+2, 2])}

CROSSREFS

Cf. A121420 (triangle); other columns: A121421, A121423.

Cf. A136737; A121413, A121417; A121427, A136741.

Sequence in context: A364621 A381574 A145161 * A060639 A068052 A379366

Adjacent sequences: A121419 A121420 A121421 * A121423 A121424 A121425

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Aug 23 2006

EXTENSIONS

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

STATUS

approved

URL: https://oeis.org/A121422

⇱ A121422 - OEIS