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A129275 Column 1 of triangle A129274; a(n) is the coefficient of q^(n+2) in the squared q-factorial of n+2. 2
1, 10, 71, 474, 3103, 20190, 131204, 853176, 5555674, 36237258, 236763125, 1549496420, 10156512792, 66669881442, 438226458380, 2884072387268, 19002479773355, 125335000366692, 827479642104143, 5468060901435850 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Robert Israel, Table of n, a(n) for n = 0..300

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

FORMULA

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

MAPLE

P:= (1+q)^2: A[0]:= 1:

for n from 1 to 50 do

  P:= normal(P * (1-q^(n+2))^2/(1-q)^2);

  A[n]:= coeff(P, q, n+2);

od:

seq(A[i], i=0..50); # Robert Israel, Jun 25 2018

PROG

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

CROSSREFS

Cf. A129274.

Sequence in context: A026772 A224292 A016098 * A049672 A221548 A037579

Adjacent sequences:  A129272 A129273 A129274 * A129276 A129277 A129278

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 07 2007

STATUS

approved

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Last modified October 21 19:27 EDT 2018. Contains 316428 sequences. (Running on oeis4.)