a(n) = 1 + Sum_{k=1..n, j=1..k} binomial(n,k)*binomial(n,j)*|Stirling_1(k,j)|*j!.

A376766

a(n) = 1 + Sum_{k=1..n, j=1..k} binomial(n,k)*binomial(n,j)*|Stirling_1(k,j)|*j!.

Terms

    a(0) =1a(1) =2a(2) =9a(3) =67a(4) =709a(5) =9766a(6) =165751a(7) =3342081a(8) =78023905a(9) =2069303986a(10) =61440372701

External references