%I #6 Dec 20 2022 19:02:41

%S 1,1,1,-3,-15,41,561,-1019,-38623,12305,4206881,7478221,-661302639,

%T -3005647943,140958927825,1143787246421,-38921417469119,

%U -494108406644959,13433349471318337,250135591701350045

%N Expansion of e.g.f.: exp(tanh(arctan(x)))=1+x+1/2!*x^2-3/3!*x^3-15/4!*x^4+41/5!*x^5...

%t With[{nn=20},CoefficientList[Series[Exp[Tanh[ArcTan[x]]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Dec 20 2022 *)

%K sign

%O 0,4

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E Definition clarified by _Harvey P. Dale_, Dec 20 2022