Number of lower triangles of an n X n 0..4 array with all row sums equal to the length of the row and all column sums equal to the length of the column.
A195640
Number of lower triangles of an n X n 0..4 array with all row sums equal to the length of the row and all column sums equal to the length of the column.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =19a(4) =391a(5) =25428a(6) =5422820a(7) =3868544673
External references
- oeis: A195640