A195643 Number of lower triangles of an n X n 0..7 array with all row sums equal to the length of the row and all column sums equal to the length of the column.

1, 1, 3, 19, 391, 25532, 5539434, 4116290300, 10699674783969, 98827025484631957, 3284291571314714878300

Offset: 1

Author

R. H. Hardin Sep 21 2011

Keywords

• nonn

Comments

Column 7 of A194644

Examples

			Some solutions for n=7
..1..............1..............1..............1..............1
..1.1............0.2............2.0............2.0............2.0
..0.3.0..........0.3.0..........3.0.0..........2.1.0..........2.1.0
..4.0.0.0........2.1.1.0........0.2.2.0........1.3.0.0........2.2.0.0
..0.2.2.0.1......2.0.1.1.1......1.1.2.0.1......1.2.2.0.0......0.1.0.3.1
..1.0.1.0.2.2....2.0.2.0.2.0....0.3.0.1.2.0....0.0.2.4.0.0....0.1.4.0.1.0
..0.0.2.4.0.0.1..0.0.1.3.0.2.1..0.0.1.3.0.2.1..0.0.1.0.3.2.1..0.1.1.1.1.2.1