A012680 arctan(tanh(x)*arctan(x))=2/2!*x^2-16/4!*x^4+80/6!*x^6+14464/8!*x^8...

0, 2, -16, 80, 14464, -1682432, 76011520, 26175092736, -10889734127616, 1790915255599104, 628448342217064448, -708415309969044275200, 277815404352915818676224, 89144743290434384702734336

Offset

0,2

Links

Table of n, a(n) for n=0..13.

Mathematica

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

Crossrefs

Sequence in context: A225959 A336174 A045905 * A012684 A234004 A053587

Adjacent sequences: A012677 A012678 A012679 * A012681 A012682 A012683

Keyword

sign

Author

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

Status

approved