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A129277 Column 1 of triangle A129276; a(n) is the coefficient of q^n in the squared q-factorial of n+1. 2
1, 2, 8, 42, 241, 1444, 8867, 55320, 349009, 2220242, 14215521, 91487834, 591285123, 3834960060, 24947236547, 162704291214, 1063516446543, 6965286759424, 45696734431169, 300262228345720, 1975679169075314 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

Eric Weisstein's World of Mathematics, q-Factorial from MathWorld.

FORMULA

a(n) = [q^n] Product_{i=1..n+1} { (1-q^i)/(1-q) }^2.

PROG

(PARI) a(n)=polcoeff(prod(i=1, n+1, (1-x^i)/(1-x))^2, n)

CROSSREFS

Cf. A129276, A129278.

Sequence in context: A153557 A231103 A114204 * A120916 A133417 A235350

Adjacent sequences:  A129274 A129275 A129276 * A129278 A129279 A129280

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 07 2007

STATUS

approved

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Last modified September 22 13:48 EDT 2021. Contains 347607 sequences. (Running on oeis4.)