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A012845
cos(sec(x)*arctanh(x))=1-1/2!*x^2-19/4!*x^4-565/6!*x^6-24743/8!*x^8...
0
1, -1, -19, -565, -24743, -1450985, -100090043, -5608180253, 703874231473, 601015521145391, 309193460848468125, 160230604230030181371, 91310347371287711776777, 58721857461984188996135495
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Cos[Sec[x]ArcTanh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Oct 25 2011 *)
CROSSREFS
Sequence in context: A035278 A092611 A008990 * A284111 A142023 A075879
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved