OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..100
MATHEMATICA
With[{nn=40}, Take[CoefficientList[Series[Sech[ArcSin[x]Sin[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] Harvey P. Dale, May 17 2012
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Definition clarified by and more terms from Harvey P. Dale, May 17 2012
STATUS
approved