OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..200
FORMULA
a(n) ~ c * (-1)^n * (2*n)! / sqrt(n), where c = sech(Pi/2)/sqrt(Pi) = 0.22485031987421343130846684736559... . - Vaclav Kotesovec, Feb 03 2015, updated Mar 17 2024
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[ArcTanh[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