A187671 Number of 3X3 0..n arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal.

24, 550, 4044, 17716, 56080, 150166, 336776, 702408, 1330728, 2385910, 3973400, 6550700, 10068336, 15247986, 22545648, 32579360, 45246528, 62983046, 84524916, 113900920, 150370548, 195521534, 249456396, 321513812, 404142192, 504603526

Offset: 1

Author

R. H. Hardin Mar 12 2011

Keywords

• nonn

Comments

Row 2 of A187670

Examples

			Some n=3 solutions for 3X3
..3..3..3....2..1..3....0..1..0....2..1..1....1..0..3....3..0..2....2..3..1
..0..1..0....2..0..2....2..1..2....2..2..0....0..3..2....0..1..2....1..0..1
..3..0..3....0..1..0....2..2..2....2..1..1....3..3..3....2..0..3....2..3..2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..31