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A298245
Expansion of e.g.f. exp(cos(tanh(x))-1) (even powers only).
0
1, -1, 12, -327, 15883, -1202524, 130394253, -19113418989, 3632485387276, -867280709024131, 253803272212372575, -89250842789856565620, 37105568909251258810585, -17991614679286735149423193, 10057557723279565571532112044, -6417980557539322347015938082111
OFFSET
0,3
FORMULA
a(n) = (2*n)! * [x^(2*n)] exp(cos(tanh(x))-1).
EXAMPLE
exp(cos(tanh(x))-1) = 1 - x^2/2! + 12*x^4/4! - 327*x^6/6! + 15883*x^8/8! - 1202524*x^10/10! + ...
MATHEMATICA
nmax = 15; Table[(CoefficientList[Series[Exp[Cos[Tanh[x]] - 1], {x, 0, 2 nmax}], x] Range[0, 2 nmax]!)[[n]], {n, 1, 2 nmax + 1, 2}]
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Jan 15 2018
STATUS
approved