A368894 a(n) = Sum_{k=0..floor(n/2)} (-n)^k * binomial(n-k,k).

1, 1, -1, -5, 5, 56, -29, -923, -119, 19855, 17711, -524160, -926771, 16339441, 45275035, -585443909, -2298643951, 23626165600, 124604211943, -1056587815835, -7261611779179, 51645640102519, 455056929514067, -2724884512463520, -30595315890959975

Offset

0,4

Links

Table of n, a(n) for n=0..24.

Formula

a(n) = [x^n] 1/(1 - x + n*x^2).

Prog

(PARI) a(n) = sum(k=0, n\2, (-n)^k*binomial(n-k, k));

Crossrefs

Cf. A171180, A368895.

Sequence in context: A196388 A073128 A189749 * A009390 A009334 A151467

Adjacent sequences: A368891 A368892 A368893 * A368895 A368896 A368897

Keyword

sign,easy

Author

Seiichi Manyama, Jan 09 2024

Status

approved