A187527 Number of (n+1)X(n+1) 0..3 arrays with each 2X2 subblock determinant nonzero and the array of 2X2 subblock determinants symmetric under 90 degree rotation.

192, 74, 35026, 20554, 164460556

Offset: 1

Author

R. H. Hardin Mar 10 2011

Keywords

• nonn

Comments

Column 3 of A187528

Examples

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