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 A009100 Expansion of e.g.f. cos(x)*cos(tanh(x)), even powers only. 1

%I #19 Jul 26 2018 08:04:18

%S 1,-2,16,-328,11712,-638720,49459840,-5159926528,697030680576,

%T -118233272496128,24578235697610752,-6139851821419921408,

%U 1813615341438397218816,-624948457889265099014144

%N Expansion of e.g.f. cos(x)*cos(tanh(x)), even powers only.

%H G. C. Greubel, <a href="/A009100/b009100.txt">Table of n, a(n) for n = 0..239</a>

%t With[{nn=30},Take[CoefficientList[Series[Cos[x]*Cos[Tanh[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Oct 07 2015 *)

%o (PARI) x='x+O('x^50); v=Vec(serlaplace(cos(x)*cos(tanh(x)))); vector(#v\2,n,v[2*n-1]) \\ _G. C. Greubel_, Jul 26 2018

%K sign

%O 0,2

%A _R. H. Hardin_

%E Extended with signs by _Olivier Gérard_, Mar 15 1997

%E Prior Mathematica program replaced by _Harvey P. Dale_, Oct 07 2015

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Last modified December 9 23:44 EST 2023. Contains 367696 sequences. (Running on oeis4.)