A187525 Number of (n+1)X(n+1) 0..1 arrays with each 2X2 subblock determinant nonzero and the array of 2X2 subblock determinants symmetric under 90 degree rotation.

6, 0, 104, 0, 9346, 0, 4278774, 0, 9966039904, 0, 118222727145122, 0, 7149579817467705382, 0, 2205539783282634028931328

Offset: 1

Author

R. H. Hardin Mar 10 2011

Keywords

• nonn

Comments

Column 1 of A187528

Examples

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