OFFSET
0,1
FORMULA
a(n) ~ (2*n)! / r^(2*n+1), where r = 0.53286199991370386509144685314983925384646... is the root of the equation arcsinh(r)+arctan(r) = 1. - Vaclav Kotesovec, Feb 05 2015
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[ArcTanh[ArcSinh[x]+ArcTan[x]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Nov 02 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved