A009559 - OEIS

A009559

Expansion of e.g.f. sin(x)/cosh(tan(x)) (odd powers only).

%I #15 Jan 22 2018 02:38:51

%S 1,-4,-4,104,5392,167936,1592384,-401669248,-50456008448,

%T -2742470413312,310319594802176,116183782320392192,

%U 12985923007223566336,-3777809306960427778048,-2961060938622580774715392

%N Expansion of e.g.f. sin(x)/cosh(tan(x)) (odd powers only).

%H G. C. Greubel, <a href="/A009559/b009559.txt">Table of n, a(n) for n = 0..240</a>

%t With[{nmax = 50}, CoefficientList[Series[Sin[x]/Cosh[Tan[x]], {x, 0, nmax}], x]*Range[0, nmax - 1]!][[2 ;; ;; 2]] (* _G. C. Greubel_, Jan 21 2018 *)

%o (PARI) x='x+O('x^50); v=Vec(serlaplace(sin(x)/cosh(tan(x)))); vector((#v-1)\2 ,n,v[2*n-1]) \\ _G. C. Greubel_, Jan 21 2018

%K sign

%O 0,2

%A _R. H. Hardin_

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