a(n) = A000166(n-1)*n*(n-1).

Terms

a(0) =6a(1) =24a(2) =180a(3) =1320a(4) =11130a(5) =103824a(6) =1067976a(7) =12014640a(8) =146845710a(9) =1938363240a(10) =27489515196a(11) =416924313624