A012231 exp(arctan(arctanh(x)))=1+x+1/2!*x^2+1/3!*x^3+1/4!*x^4+9/5!*x^5...

1, 1, 1, 1, 1, 9, 49, 281, 1345, 13233, 105441, 1179729, 10336833, 144386553, 1580651409, 25501409961, 316289380737, 5869292202465, 83559601907649, 1744083324947745, 27709107620492673, 643531258862953065

Offset: 0

Author

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

Keywords

• nonn

Programs

Mathematica

With[{nn=30},CoefficientList[Series[Exp[ArcTan[ArcTanh[x]]],{x,0,nn}],x] Range[0,nn]!] (* Ray Chandler, Nov 28 2016 *)