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A343845
a(n) = Sum_{k=0..floor(n/2)} A109449(n-k, k).
0
1, 1, 2, 4, 9, 27, 93, 392, 1898, 10493, 64885, 443916, 3326317, 27085015, 238073306, 2246348560, 22643042325, 242808804441, 2759740869777, 33138397797908, 419171443909394, 5570771017483187, 77603014042711369, 1130712331125929112, 17198408830271090233
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
Cf. A109449.
Sequence in context: A148085 A003320 A007876 * A349404 A332979 A176068
KEYWORD
nonn
AUTHOR
Peter Luschny, May 06 2021
STATUS
approved