A012835 arctan(sec(x)*tanh(x))=x-1/3!*x^3+25/5!*x^5-761/7!*x^7+42065/9!*x^9...

1, -1, 25, -761, 42065, -3898321, 521329705, -96017526281, 23356125062945, -7240133620964641, 2786977252450841785, -1304375789021987253401, 729394652578427432666225, -480281453260247282387992561

Offset: 0

Author

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

Keywords

• sign

Programs

Mathematica

With[{nn=30},Take[CoefficientList[Series[ArcTan[Sec[x]Tanh[x]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* Harvey P. Dale, Jul 30 2020 *)