A009292 - OEIS

%I #13 Mar 23 2019 11:39:53

%S 1,1,2,4,4,-4,-32,-104,400,5392,3680,-167936,-719168,1592384,45313024,

%T 401669248,-1201882880,-50456008448,-190738937344,2742470413312,

%U 41876315935744,310319594802176,-3729103532367872,-116183782320392192

%N Expansion of exp(x)/cos(tanh(x)).

%t With[{nn=30},CoefficientList[Series[Exp[x]/Cos[Tanh[x]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Mar 23 2019 *)

%K sign,easy

%O 0,3

%A _R. H. Hardin_

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

%E Previous Mathematica program replaced by _Harvey P. Dale_, Mar 23 2019