OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..445
FORMULA
a(n) ~ Pi*exp(-1/4-n)*n^(n+1) if n is even, a(n) ~ 2*Pi*exp(3/4-n)*(n-1)^n if n is odd. - Vladimir Reshetnikov, Oct 19 2016
MAPLE
a := n -> 2^n*floor(n/2)!*GAMMA(ceil((n+1)/2), -1/4)*exp(-1/4):
seq(simplify(a(n)), n=0..22);
MATHEMATICA
a[n_] := 2^n Floor[n/2]! Gamma[Ceiling[(1 + n)/2], -1/4] Exp[-1/4];
FunctionExpand@Table[a[n], {n, 0, 22}]
PROG
(PARI) for(n=0, 20, print1(round(2^n*(floor(n/2))!*exp(-1/4)* incgam(ceil((n +1)/2), -1/4)), ", ")) \\ G. C. Greubel, May 16 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Oct 17 2016
STATUS
approved