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A012061
sec(sin(arctanh(x)))=1+1/2!*x^2+9/4!*x^4+201/6!*x^6+7921/8!*x^8...
0
1, 1, 9, 201, 7921, 447281, 28121145, 230243001, -940995291295, -539358796035359, -280768914546419735, -156059839698555664599, -96215805882840361663151, -66431831409927100446899439
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sec[Sin[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 24 2021 *)
CROSSREFS
Sequence in context: A197077 A093708 A052145 * A012168 A012133 A012038
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved