OFFSET
0,1
FORMULA
a(n) ~ (2*n+1)! / r^(2*n+2), where r = 0.825607669071161851569946... is the real root of the equation tan(r)*sinh(r)=1. - Vaclav Kotesovec, Oct 24 2013
MATHEMATICA
Table[n!*SeriesCoefficient[ArcTanh[Sinh[x]*Tan[x]], {x, 0, n}], {n, 2, 40, 2}] (* Vaclav Kotesovec, Oct 24 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved