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A121425 Main diagonal of rectangular table A121424. 6
1, 2, 12, 118, 1605, 27816, 585046, 14459138, 410368743, 13146830110, 469123986529, 18447791712945, 792514583941223, 36925394368325295, 1854525584914459755, 99872579714406393286, 5740977285851988017769 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

Also main diagonal of square array A136733.

FORMULA

a(n) = [A121412^(n+1)](n,0) for n>=0; i.e., (n+1)-th term of column 0 in matrix power A121412^(n+1).

PROG

(PARI) {a(n)=local(H=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, B[i, j]=(H^i)[i-1, j]); )); H=B); return((H^(n+1))[n+1, 1])}

CROSSREFS

Cf. A121424, A121412.

Cf. A136733; A101483, A121418, A121421.

Sequence in context: A012628 A012623 A009742 * A132692 A009546 A009748

Adjacent sequences:  A121422 A121423 A121424 * A121426 A121427 A121428

KEYWORD

nonn

AUTHOR

Paul D. Hanna (pauldhanna(AT)juno.com), Aug 26 2006

EXTENSIONS

Edited by N. J. A. Sloane (njas(AT)research.att.com), Oct 30 2008 at the suggestion of R. J. Mathar

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Last modified February 15 13:26 EST 2012. Contains 205802 sequences.