A012727 exp(arctanh(x)*arctan(x))=1+2/2!*x^2+12/4!*x^4+328/6!*x^6+13328/8!*x^8...

1, 2, 12, 328, 13328, 1160352, 123701952, 22207125120, 4532782825728, 1380071532433920, 459909185638812672, 212375023941305272320, 104929881035116227072000, 68350141067274779587092480

Offset: 0

Author

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

Keywords

• nonn

Programs

Mathematica

With[{nn=30},Take[CoefficientList[Series[Exp[ArcTanh[x]*ArcTan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* Ray Chandler, Nov 28 2016 *)