OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..220
FORMULA
a(n) ~ c * (-1)^n * (2*n)! * n / r^(2*n), where r = sin(arcsinh(Pi/2)) = 0.9436207924237..., c = 0.79859796313... . - Vaclav Kotesovec, Feb 04 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[Tanh[Sin[ArcSinh[x]]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 03 2015 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved