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A009115 Expansion of e.g.f. cos(x)/exp(tanh(x)). 1
1, -1, 0, 4, -12, -12, 216, -296, -5296, 25200, 168128, -1885952, -5391680, 163728576, -38412672, -16916558720, 61881368832, 2050105730816, -16576603568128, -282656394482688, 4120672559178752, 42100913802486784 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..250

MATHEMATICA

With[{nmax = 30}, CoefficientList[Series[Cos[x]/Exp[Tanh[x]], {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Jul 26 2018 *)

PROG

(PARI) x='x+O('x^30); Vec(serlaplace(cos(x)/exp(tanh(x)))) \\ G. C. Greubel, Jul 26 2018

(MAGMA) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cos(x)/Exp(Tanh(x)))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 26 2018

CROSSREFS

Sequence in context: A209019 A202636 A239194 * A051434 A074138 A120252

Adjacent sequences:  A009112 A009113 A009114 * A009116 A009117 A009118

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified April 23 05:42 EDT 2021. Contains 343199 sequences. (Running on oeis4.)