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A330517
Expansion of e.g.f. Product_{k>=1} sech(x^k) (even powers only).
4
1, -1, -7, -241, -4495, -652801, -15004375, -7047990769, 1597056262625, -360304327144321, 286464442762907225, 560117092794518159, 78257061390674957994065, 5684812583023438995911039, 45666128878264725133259682185
OFFSET
0,3
MATHEMATICA
nmax = 14; Table[(CoefficientList[Series[Product[Sech[x^k], {k, 1, nmax}], {x, 0, 2 nmax}], x] Range[0, 2 nmax]!)[[n]], {n, 1, 2 nmax + 1, 2}]
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Dec 17 2019
STATUS
approved