A012227 tanh(arctan(tanh(x)))=x-6/3!*x^3+176/5!*x^5-12016/7!*x^7...

1, -6, 176, -12016, 1469696, -280971776, 77198422016, -28793654081536, 13988424620507136, -8578076577450295296, 6478101995566379565056, -5906079803365219349037056, 6394716233788355978540875776

Offset: 0

Author

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

Keywords

• sign

Crossrefs

Cf. A101921.

Programs

Mathematica

With[{nn=30},Take[CoefficientList[Series[Tanh[ArcTan[Tanh[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* Harvey P. Dale, Dec 08 2018 *)