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%I #19 Jul 26 2018 08:03:23
%S 1,-1,21,-597,26537,-1834249,180938109,-23781199197,3989919982673,
%T -830092069266577,209479116176732901,-62986349633232396261,
%U 22231865269167169440761,-9096170536950779556167833
%N Expansion of e.g.f. cos(tanh(x)*cos(x)), even powers only.
%H G. C. Greubel, <a href="/A009091/b009091.txt">Table of n, a(n) for n = 0..238</a>
%p seq(coeff(series(factorial(n)*cos(tanh(x)*cos(x)), x,n+1),x,n),n=0..30,2); # _Muniru A Asiru_, Jul 26 2018
%t With[{nmax = 60}, CoefficientList[Series[Cos[Tanh[x]*Cos[x]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* _G. C. Greubel_, Jul 25 2018 *)
%o (PARI) x='x+O('x^50); v=Vec(serlaplace(cos(tanh(x)*cos(x)))); vector(#v\2,n,v[2*n-1]) \\ _G. C. Greubel_, Jul 25 2018
%K sign
%O 0,3
%A _R. H. Hardin_
%E Extended with signs by _Olivier Gérard_, Mar 15 1997
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