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A304444 Coefficient of x^n in Product_{k>=1} 1/(1-x^k)^(2*n). 6
1, 2, 14, 98, 726, 5512, 42614, 333608, 2636326, 20985272, 168012824, 1351507830, 10914317934, 88432329546, 718545161208, 5852747363518, 47774241056710, 390702055798978, 3200542803221192, 26257321971526646, 215705170816632376, 1774181109262878848 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000

FORMULA

a(n) ~ c * d^n / sqrt(n), where d = 8.42516721063251541777601555584151410936132980324698494327338254953123205... and c = 0.29923152009652750283923119244187982714171590056794904644563876...

MATHEMATICA

nmax = 25; Table[SeriesCoefficient[Product[1/(1-x^k)^(2*n), {k, 1, n}], {x, 0, n}], {n, 0, nmax}]

nmax = 25; Table[SeriesCoefficient[1/QPochhammer[x]^(2*n), {x, 0, n}], {n, 0, nmax}]

CROSSREFS

Cf. A000712, A008485, A161870, A171803, A304443.

Sequence in context: A286445 A322262 A109808 * A247481 A037516 A037719

Adjacent sequences:  A304441 A304442 A304443 * A304445 A304446 A304447

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, May 12 2018

STATUS

approved

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Last modified January 28 00:32 EST 2020. Contains 331313 sequences. (Running on oeis4.)