A368895 - OEIS

%I #9 Jan 09 2024 08:48:09

%S 1,1,1,-2,-7,-14,13,113,337,19,-2579,-10867,-9911,71852,431229,741181,

%T -2178783,-20081708,-51012467,58414532,1061935641,3651310699,1841181,

%U -62090909433,-279070619279,-250335322449,3913178936941,22877592319648,38634162528361

%N a(n) = Sum_{k=0..floor(n/3)} (-n)^k * binomial(n-2*k,k).

%F a(n) = [x^n] 1/(1 - x + n*x^3).

%o (PARI) a(n) = sum(k=0, n\3, (-n)^k*binomial(n-2*k, k));

%Y Cf. A368891, A368894.

%K sign,easy

%O 0,4

%A _Seiichi Manyama_, Jan 09 2024