OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..232
FORMULA
a(n) ~ (2*n)! * 4 * cos(arcsinh(Pi/2)) / (sqrt(4+Pi^2) * arcsinh(Pi/2)^(2*n+1)). - Vaclav Kotesovec, Jan 22 2015
MATHEMATICA
nn = 20; Table[(CoefficientList[Series[Cos[x]*Sec[Sinh[x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 22 2015 *)
PROG
(PARI) x='x+O('x^50); v=Vec(serlaplace(cos(x)/cos(sinh(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended and signs tested by Olivier Gérard, Mar 15 1997
STATUS
approved