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A013462 Expansion of e.g.f.: exp(arctan(x)-arctanh(x))=1-4/3!*x^3+160/6!*x^6-1440/7!*x^7... 0
1, 0, 0, -4, 0, 0, 160, -1440, 0, -17920, 691200, -7257600, 3942400, -395366400, 14125363200, -175791616000, 295206912000, -24049778688000, 902471385088000, -13090802909184000, 43911376404480000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..20.

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Exp[ArcTan[x]-ArcTanh[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 25 2016 *)

CROSSREFS

Sequence in context: A054376 A071608 A013451 * A326862 A222325 A101453

Adjacent sequences:  A013459 A013460 A013461 * A013463 A013464 A013465

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, May 25 2016

STATUS

approved

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Last modified December 9 08:41 EST 2021. Contains 349627 sequences. (Running on oeis4.)