A009556 - OEIS

%I #20 May 02 2024 14:41:24

%S 1,2,-24,104,5824,-385408,15920256,-160063744,-67251703808,

%T 9821117788160,-551206277726208,-106679023552528384,

%U 37135946330613907456,-2111279822539107794944,-3285803845056084678279168

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

%H G. C. Greubel, <a href="/A009556/b009556.txt">Table of n, a(n) for n = 0..240</a>

%t With[{nmax = 50}, CoefficientList[Series[Sin[x]/Cos[Tanh[x]],{x,0,nmax} ], x]*Range[0, nmax - 1]!][[2 ;; ;; 2]] (* _G. C. Greubel_, Jan 20 2018 *)

%o (PARI) x='x+O('x^50); v=Vec(serlaplace(sin(x)/cos(tanh(x))));  vector((#v-1)\2, n,v[2*n-1]) \\ _G. C. Greubel_, Jan 20 2018

%K sign

%O 0,2

%A _R. H. Hardin_

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