OFFSET
0,1
MATHEMATICA
With[{nn=50}, Take[CoefficientList[Series[ArcSinh[Sec[x]-Sech[x]], {x, 0, nn}], x]Range[0, nn]!, {3, -1, 4}]] (* Harvey P. Dale, Jan 22 2013 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
More terms from N. J. A. Sloane, Dec 17 2011
STATUS
approved