A187530 Number of 4X4 0..n arrays with each 2X2 subblock determinant nonzero and the array of 2X2 subblock determinants symmetric under 90 degree rotation.

104, 3790, 35026, 220802, 727842, 2327574, 5366230, 13768228, 28531154, 54987216, 90945478

Offset: 1

Author

R. H. Hardin Mar 10 2011

Keywords

• nonn

Comments

Row 3 of A187528

Examples

			Some solutions for 4X4
..3..1..2..1....3..3..1..3....3..0..3..1....2..3..3..3....2..1..0..1
..1..0..1..0....2..3..0..3....1..2..0..2....1..0..1..0....2..0..2..1
..0..1..0..1....1..0..1..0....3..0..3..3....3..3..0..3....0..1..0..1
..1..0..1..0....0..3..0..3....0..2..0..2....1..0..1..2....2..3..2..2