a(n) = n!^2*(Sum_{k=1..n} 1/k).

A329930

a(n) = n!^2*(Sum_{k=1..n} 1/k).

Terms

    a(0) =0a(1) =1a(2) =6a(3) =66a(4) =1200a(5) =32880a(6) =1270080a(7) =65862720a(8) =4418426880a(9) =372523898880

External references