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A012229
cosh(arctan(tanh(x)))=1+1/2!*x^2-15/4!*x^4+561/6!*x^6-40415/8!*x^8...
0
1, 1, -15, 561, -40415, 4825121, -866056815, 218527875281, -73838559553215, 32207514779999041, -17624680185473393615, 11826144583278421964401, -9549876975469294700602015, 9137286945784401729622059361
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Cosh[ArcTan[Tanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 11 2019 *)
CROSSREFS
Sequence in context: A115918 A110840 A012178 * A212931 A027462 A329122
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved