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A012505 arctanh(cos(x)*arctan(x))=x-3/3!*x^3-27/5!*x^5+777/7!*x^7+48905/9!*x^9... 0
1, -3, -27, 777, 48905, -4320107, -424303635, 77237001761, 20512289602833, -6321209675239123, -1704909797900721931, 812189572458422888249, 493715837509806144441881, -331434668084376519747747387 (list; graph; refs; listen; history; text; internal format)
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 A009066

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

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Last modified July 25 10:07 EDT 2021. Contains 346289 sequences. (Running on oeis4.)