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

A351795

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

Terms

    a(0) =1a(1) =1a(2) =4a(3) =30a(4) =396a(5) =8360a(6) =256470a(7) =10619952a(8) =564959528a(9) =37370475648

External references