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A326862 E.g.f.: Product_{k>=1} (1 + x^(4*k-1)/(4*k-1)) / (1 - x^(4*k-1)/(4*k-1)). 2
1, 0, 0, 4, 0, 0, 160, 1440, 0, 26880, 691200, 7257600, 11827200, 395366400, 14125363200, 185119334400, 442810368000, 24049778688000, 919255538073600, 13662913904640000, 54833495408640000, 3627817738960896000, 142917996623560704000, 2442221696292618240000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..400

FORMULA

a(n) ~ exp(-gamma/2) * n! / (2*sqrt(n)), where gamma is the Euler-Mascheroni constant A001620.

MATHEMATICA

nmax = 30; CoefficientList[Series[Product[(1+x^(4*k-1)/(4*k-1))/(1-x^(4*k-1)/(4*k-1)), {k, 1, Floor[nmax/4]+1}], {x, 0, nmax}], x] * Range[0, nmax]!

CROSSREFS

Cf. A326855, A326779.

Cf. A305199, A326859, A326860, A326863.

Sequence in context: A071608 A013451 A013462 * A222325 A101453 A222399

Adjacent sequences:  A326859 A326860 A326861 * A326863 A326864 A326865

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Jul 27 2019

STATUS

approved

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Last modified October 17 13:24 EDT 2021. Contains 348049 sequences. (Running on oeis4.)