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A012236
tanh(arctan(arctanh(x)))=x-2/3!*x^3+24/5!*x^5-496/7!*x^7+24192/9!*x^9...
0
1, -2, 24, -496, 24192, -1246464, 150408192, -12132673536, 3380973895680, -253363927449600, 217523969745223680, 4682388187242823680, 35388810383588767825920, 8821171867345211810119680
OFFSET
0,2
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[ArcTan[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Ray Chandler, Nov 28 2016 *)
CROSSREFS
Sequence in context: A360975 A052712 A133413 * A186414 A359848 A187658
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved