A012207 arcsinh(arctan(arctan(x)))=x-5/3!*x^3+137/5!*x^5-9141/7!*x^7...

1, -5, 137, -9141, 1130993, -225155941, 66037540345, -26862446793685, 14500070037397089, -10041538909269213637, 8686453887771982767337, -9185311291945403768547829, 11662015255583014905028727633

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcSinh[ArcTan[ArcTan[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jul 16 2013 *)

Crossrefs

Sequence in context: A339566 A012215 A012142 * A192640 A192641 A192642

Adjacent sequences: A012204 A012205 A012206 * A012208 A012209 A012210

Keyword

sign

Author

Patrick Demichel

Extensions

Definition clarified by Harvey P. Dale, Jul 16 2013

Status

approved