OFFSET
0,2
FORMULA
a(n) ~ (-1)^n * cosh(1) * 2^(2*n+3) * n^(2*n) / ((4+Pi^2*cosh(1)^2) * exp(2*n)). - Vaclav Kotesovec, Nov 01 2013
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[ArcTanh[ArcSinh[x]Cos[x]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 20 2012 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved