A012224 arctan(arctan(tanh(x)))=x-6/3!*x^3+184/5!*x^5-13584/7!*x^7...

1, -6, 184, -13584, 1840768, -397140224, 124961670144, -54024939321344, 30732245464219648, -22258174840910315520, 20000813079319781048320, -21837489688957057049821184, 28476242253811580631861166080

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Mathematica

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

Crossrefs

Sequence in context: A222887 A012208 A012181 * A274272 A175237 A222335

Adjacent sequences: A012221 A012222 A012223 * A012225 A012226 A012227

Keyword

sign

Author

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

Status

approved