Triangle read by rows: T(n, k) = Sum_{t=k..n-3} (-1)^(t-k)*(n-t)!*binomial(t,k)*binomial(n-3,t).

Terms

a(0) =6a(1) =18a(2) =6a(3) =78a(4) =36a(5) =6a(6) =426a(7) =234a(8) =54a(9) =6a(10) =2790a(11) =1704a(12) =468a(13) =72a(14) =6a(15) =21234a(16) =13950a(17) =4260a(18) =780a(19) =90a(20) =6a(21) =183822a(22) =127404a(23) =41850a(24) =8520a(25) =1170a(26) =108a(27) =6a(28) =1781802a(29) =1286754