a(n) = Sum_{k=0..n} Stirling2(n,k) * (n!/k!)^2.

A385750

a(n) = Sum_{k=0..n} Stirling2(n,k) * (n!/k!)^2.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =64a(4) =1681a(5) =78651a(6) =5891041a(7) =653545390a(8) =101785047169

External references