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

%I #21 Jul 24 2018 11:49:42

%S 1,-1,17,-457,19777,-1305489,122670033,-15462740633,2502900454401,

%T -504155298072609,123438576028985873,-36064963500185608553,

%U 12385279694301347665473,-4936243039568368083279793,2258619438301840395444067537,-1175352020113183347337766918201

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

%H G. C. Greubel, <a href="/A009051/b009051.txt">Table of n, a(n) for n = 0..238</a>

%t With[{nn=30},Take[CoefficientList[Series[Cos[Sin[x]/Cosh[x]],{x,0,nn}],x] Range[ 0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Mar 27 2013 *)

%o (PARI) x='x+O('x^60); v=Vec(serlaplace(cos(sin(x)/cosh(x)))); vector(#v\2,n,v[2*n-1]) \\ _G. C. Greubel_, Jul 23 2018

%K sign

%O 0,3

%A _R. H. Hardin_

%E Extended with signs by _Olivier GĂ©rard_, Mar 15 1997

%E More terms from _Harvey P. Dale_, Mar 27 2013