OFFSET
0,4
COMMENTS
sec(x) = 1/cos(x).
LINKS
Robert Israel, Table of n, a(n) for n = 0..444
FORMULA
E.g.f.: cos(x)^(-x).
a(n) ~ (2*n/Pi)^(n+Pi/2)*sqrt(2*Pi/n)*exp(-n)/Gamma(Pi/2). - Vaclav Kotesovec, Sep 25 2013
MAPLE
a:= n-> n! * coeff(series(cos(x)^(-x), x, n+1), x, n):
seq(a(n), n=0..30); # Alois P. Heinz, Aug 18 2012
MATHEMATICA
f[x_] := Sec[x]^x; Table[Derivative[n] [f][0], {n, 0, 25}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 18 2012
STATUS
approved