A368894 - OEIS

%I #7 Jan 09 2024 08:48:06

%S 1,1,-1,-5,5,56,-29,-923,-119,19855,17711,-524160,-926771,16339441,

%T 45275035,-585443909,-2298643951,23626165600,124604211943,

%U -1056587815835,-7261611779179,51645640102519,455056929514067,-2724884512463520,-30595315890959975

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

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

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

%Y Cf. A171180, A368895.

%K sign,easy

%O 0,4

%A _Seiichi Manyama_, Jan 09 2024