a(n) = n! * Sum_{k=0..floor(n/3)} (-1)^k / (n-3*k)!.

A337750

a(n) = n! * Sum_{k=0..floor(n/3)} (-1)^k / (n-3*k)!.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =-5a(4) =-23a(5) =-59a(6) =601a(7) =4831a(8) =19825a(9) =-302903a(10) =-3478319a(11) =-19626749a(12) =399831961a(13) =5968795405a(14) =42864819817

External references