Lah numbers: a(n) = (n-1)*n!/2.

Terms

a(0) =1a(1) =6a(2) =36a(3) =240a(4) =1800a(5) =15120a(6) =141120a(7) =1451520a(8) =16329600a(9) =199584000a(10) =2634508800a(11) =37362124800a(12) =566658892800