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A012122
sech(arcsin(arcsinh(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+4073/8!*x^8...
0
1, -1, 5, -109, 4073, -295161, 30105261, -4622444709, 920180967249, -244553774342769, 80285311139524821, -32887829518696856925, 16096767138947015536185, -9423401435342942243589225
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSin[ArcSinh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 19 2016 *)
CROSSREFS
Sequence in context: A371882 A376462 A014180 * A012091 A322896 A296743
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved