A012215 arctan(arctan(arcsinh(x)))=x-5/3!*x^3+137/5!*x^5-9029/7!*x^7...

1, -5, 137, -9029, 1089713, -209177605, 58539026361, -22507046465157, 11386223123252449, -7334290106238920453, 5861710212500532385641, -5692596379677558396424645, 6602985113623111671589590673

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcTan[ArcTan[ArcSinh[x]]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 20 2012 *)

Crossrefs

Sequence in context: A248523 A159546 A339566 * A012142 A012207 A192640

Adjacent sequences: A012212 A012213 A012214 * A012216 A012217 A012218

Keyword

sign

Author

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

Extensions

Definition clarified by Harvey P. Dale, Oct 20 2012

Status

approved