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A009095 Expansion of e.g.f. cos(tanh(x)/cos(x)), even powers only. 1

%I #16 Jul 26 2018 08:03:39

%S 1,-1,-3,-117,-903,-111529,687093,-320199453,44530596081,

%T -254346923089,2006766293627373,141849542553657147,

%U 144420752722329270633,17706925736601628695047,16789499049770600380859877

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

%H G. C. Greubel, <a href="/A009095/b009095.txt">Table of n, a(n) for n = 0..240</a>

%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 26 2018 *)

%o (PARI) x='x+O('x^60); v=Vec(serlaplace(cos(tanh(x)/cos(x)))); vector(#v\2,n,v[2*n-1]) \\ _G. C. Greubel_, Jul 26 2018

%K sign

%O 0,3

%A _R. H. Hardin_

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

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Last modified April 20 21:11 EDT 2024. Contains 371845 sequences. (Running on oeis4.)