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

A357192

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

Terms

    a(0) =1a(1) =0a(2) =0a(3) =6a(4) =24a(5) =120a(6) =23760a(7) =327600a(8) =5201280a(9) =1283688000a(10) =37574409600

External references