OFFSET
0,3
FORMULA
a(n) ~ n! * (1 + (-1)^n + (1-(-1)^n)*Pi / sqrt(4+Pi^2)) / (log((Pi + sqrt(4 + Pi^2))/2))^(n+1). - Vaclav Kotesovec, Jan 22 2015
MATHEMATICA
Exp[ x ]/Cos[ Sinh[ x ] ]
CoefficientList[Series[E^x*Sec[Sinh[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Extended and signs tested Mar 15 1997 by Olivier Gérard.
STATUS
approved