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A012224 arctan(arctan(tanh(x)))=x-6/3!*x^3+184/5!*x^5-13584/7!*x^7... 0
1, -6, 184, -13584, 1840768, -397140224, 124961670144, -54024939321344, 30732245464219648, -22258174840910315520, 20000813079319781048320, -21837489688957057049821184, 28476242253811580631861166080 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[ArcTan[ArcTan[Tanh[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Ray Chandler, Nov 28 2016 *)

CROSSREFS

Sequence in context: A222887 A012208 A012181 * A274272 A175237 A222335

Adjacent sequences:  A012221 A012222 A012223 * A012225 A012226 A012227

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified September 23 19:41 EDT 2020. Contains 337315 sequences. (Running on oeis4.)