OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..220
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[ArcSinh[Tan[x]^2], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Dec 14 2014 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Prepended a(0)=0 by Vaclav Kotesovec, Nov 28 2015
STATUS
approved