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A187006 A diagonal of triangle A187005. 5
1, 2, 6, 29, 202, 1880, 22108, 315784, 5322126, 103541022, 2285965792, 56501970700, 1546339364952, 46433615292128, 1518172222889000, 53695946069029290, 2042960241832903824, 83207255745283689726 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Definition of triangle: A187005(n,k) = [y^k] R_{n-1}(y+y^2) for k=1..n where R_n(y) is the n-th row polynomial for n>1 with R_1(y)=y.

LINKS

Table of n, a(n) for n=1..18.

PROG

(PARI) {a(n)=local(Rn=y); for(m=1, n+1, Rn=subst(truncate(Rn), y, y+y^2+y*O(y^m))); polcoeff(Rn, n, y)}

CROSSREFS

Cf. A187005, A135081, A187007, A187008, A187009.

Sequence in context: A260578 A296792 A241462 * A321961 A088957 A030538

Adjacent sequences:  A187003 A187004 A187005 * A187007 A187008 A187009

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 02 2011

STATUS

approved

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Last modified July 4 14:15 EDT 2020. Contains 335448 sequences. (Running on oeis4.)