A012505 arctanh(cos(x)*arctan(x))=x-3/3!*x^3-27/5!*x^5+777/7!*x^7+48905/9!*x^9...

1, -3, -27, 777, 48905, -4320107, -424303635, 77237001761, 20512289602833, -6321209675239123, -1704909797900721931, 812189572458422888249, 493715837509806144441881, -331434668084376519747747387

Offset

0,2

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[ArcTanh[Cos[x]ArcTan[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Mar 24 2013 *)

Crossrefs

Sequence in context: A185149 A326086 A194500 * A331439 A085521 A377760

Adjacent sequences: A012502 A012503 A012504 * A012506 A012507 A012508

Keyword

sign

Author

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

Extensions

Definition clarified by Harvey P. Dale, Mar 24 2013

Status

approved