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

A362304

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

Terms

    a(0) =1a(1) =1a(2) =1a(3) =-5a(4) =-31a(5) =-99a(6) =1201a(7) =13231a(8) =70785a(9) =-1362311a(10) =-21562399a(11) =-161746749a(12) =4263108961a(13) =87979472725a(14) =849097038609

External references