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

A047799

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

Terms

    a(0) =1a(1) =1a(2) =3a(3) =40a(4) =1015a(5) =40631a(6) =2334766a(7) =180836664a(8) =18067408311

External references