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

A368505

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

Terms

    a(0) =1a(1) =1a(2) =6a(3) =60a(4) =900a(5) =18945a(6) =536046a(7) =19750864a(8) =923023368a(9) =53456736825

External references