OFFSET
0,4
MATHEMATICA
With[{nn=40}, Take[CoefficientList[Series[Sech[Sec[x]Tanh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jun 20 2017 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
More terms from Harvey P. Dale, Jun 20 2017
STATUS
approved