OFFSET
0,3
FORMULA
a(n) ~ 2^(n+2) * n! / Pi^(n+1). - Vaclav Kotesovec, May 06 2021
MAPLE
seq(add(A109449(n-k, k), k = 0..n/2), n = 0..25);
MATHEMATICA
Table[Sum[Binomial[n-k, k] * 2^(n-2*k) * Abs[EulerE[n-2*k, 1/2] + EulerE[n-2*k, 1]], {k, 0, Floor[n/2]}] - (1 + (-1)^n)/2, {n, 0, 25}] (* Vaclav Kotesovec, May 06 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, May 06 2021
STATUS
approved