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

A320502

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

Terms

    a(0) =1a(1) =1a(2) =5a(3) =50a(4) =842a(5) =21644a(6) =792676a(7) =39297600a(8) =2536525008a(9) =206794669104

External references