a(n) = Sum_{k=0..n} Stirling1(n,k) * Stirling2(n,k) * (k!)^2.

A382794

a(n) = Sum_{k=0..n} Stirling1(n,k) * Stirling2(n,k) * (k!)^2.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =2a(4) =-418a(5) =-14676a(6) =-234344a(7) =18565056a(8) =2659703616a(9) =169046742960

External references