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

A351765

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

Terms

    a(0) =1a(1) =1a(2) =12a(3) =279a(4) =11536a(5) =746525a(6) =69768036a(7) =8902181575

External references