a(n) = Sum_{k=1..n} (-1)^(n-k) * Stirling1(n,k) * (k-1)! * sigma_2(k), where sigma_2 = A001157.

A330495

a(n) = Sum_{k=1..n} (-1)^(n-k) * Stirling1(n,k) * (k-1)! * sigma_2(k), where sigma_2 = A001157.

Terms

    a(0) =1a(1) =6a(2) =37a(3) =307a(4) =2858a(5) =32060a(6) =405830a(7) =5777354a(8) =91400200a(9) =1593023040a(10) =30251766840a(11) =622016655816

External references