Triangle, read by rows, T(n, k) = binomial(n-1,k-1)*n!/k! + binomial(n-1, n-k)* n!/(n-k+1)! - n!.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =1a(6) =1a(7) =24a(8) =24a(9) =1a(10) =1a(11) =140a(12) =120a(13) =140a(14) =1a(15) =1a(16) =1110a(17) =780a(18) =780a(19) =1110a(20) =1a(21) =1a(22) =10122a(23) =8190a(24) =3360a(25) =8190a(26) =10122a(27) =1a(28) =1a(29) =100856