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A009110 Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only. 1

%I

%S 1,-2,4,32,400,-3680,-719168,-45313024,-1201882880,190738937344,

%T 41876315935744,3729103532367872,-442609357053390848,

%U -294584246423093633024,-75554765797484141625344,-7698772402123265223688192,3712165683571701387680088064

%N Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only.

%H G. C. Greubel, <a href="/A009110/b009110.txt">Table of n, a(n) for n = 0..243</a>

%t With[{nn=40},Take[CoefficientList[Series[Cos[x]/Cosh[Tan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, May 06 2016 *)

%o (PARI) x='x+O('x^50); v=Vec(serlaplace(cos(x)/cosh(tan(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 GĂ©rard_, Mar 15 1997

%E More terms from and prior Mathematica program replaced by _Harvey P. Dale_, May 06 2016

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Last modified March 27 12:57 EDT 2023. Contains 361570 sequences. (Running on oeis4.)