Permanent of the n-th principal submatrix of A204545.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =2a(5) =6a(6) =8a(7) =48a(8) =288a(9) =1344a(10) =3456a(11) =28512a(12) =212544a(13) =1425600a(14) =6220800a(15) =61378560a(16) =600514560a(17) =5185658880a(18) =31684608000a(19) =374492160000