OFFSET
0,2
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[Tan[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Sep 06 2023 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved