A368895 a(n) = Sum_{k=0..floor(n/3)} (-n)^k * binomial(n-2*k,k).
1, 1, 1, -2, -7, -14, 13, 113, 337, 19, -2579, -10867, -9911, 71852, 431229, 741181, -2178783, -20081708, -51012467, 58414532, 1061935641, 3651310699, 1841181, -62090909433, -279070619279, -250335322449, 3913178936941, 22877592319648, 38634162528361
Offset: 0
Programs
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PARI
a(n) = sum(k=0, n\3, (-n)^k*binomial(n-2*k, k));
Formula
a(n) = [x^n] 1/(1 - x + n*x^3).