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A012844 arctan(sec(x)*arctanh(x))=x+3/3!*x^3-7/5!*x^5-917/7!*x^7-7183/9!*x^9... 0
1, 3, -7, -917, -7183, 3803987, 316369129, -40892465221, -12655402122271, 1539257113273507, 1652188971379360217, 198029913991075323147, -231213557728594141960239, -76270663840340687485107213 (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[ArcTan[Sec[x]ArcTanh[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Sep 18 2013 *)

CROSSREFS

Sequence in context: A092568 A055624 A065244 * A104052 A062625 A175986

Adjacent sequences:  A012841 A012842 A012843 * A012845 A012846 A012847

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, Sep 18 2013

STATUS

approved

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Last modified October 19 03:10 EDT 2021. Contains 348073 sequences. (Running on oeis4.)