OFFSET
0,2
FORMULA
Lim sup n->infinity |a(n)|/(2^(4*n+3)*(2*n)!/(Pi^2 + 4*(log(2+sqrt(3)))^2)^(n+1/2)) = 1. - Vaclav Kotesovec, Oct 24 2013
MATHEMATICA
Table[n!*SeriesCoefficient[ArcTanh[Cos[x]*Sin[x]], {x, 0, n}], {n, 1, 40, 2}] (* Vaclav Kotesovec, Oct 24 2013 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved