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A124383 O.g.f.: A(x) = Sum_{n>=0} x^n*Product_{k=0..n} (1 + k*x)^2. 0
1, 1, 3, 8, 26, 91, 349, 1431, 6253, 28860, 140064, 711433, 3768601, 20754377, 118513699, 700096184, 4269686754, 26835429731, 173541095213, 1153074832175, 7861658903709, 54937031541660, 393050395468752, 2876341596372209 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..23.

EXAMPLE

A(x) = 1 + x*(1+x)^2 + x^2*(1+x)^2*(1+2x)^2 + x^3*(1+x)^2*(1+2x)^2*(1+3x)^2 +...

PROG

(PARI) a(n)=polcoeff(sum(k=0, n, x^k*prod(j=0, k, 1+j*x+x*O(x^n))^2), n)

CROSSREFS

Sequence in context: A242903 A081497 A028270 * A148819 A148820 A148821

Adjacent sequences:  A124380 A124381 A124382 * A124384 A124385 A124386

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Oct 28 2006

STATUS

approved

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Last modified June 15 08:06 EDT 2021. Contains 345048 sequences. (Running on oeis4.)