A187696 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 horizontal and vertical reflection.

6, 0, 104, 0, 9350, 0, 4280018, 0, 9966761956, 0, 118224466422070, 0, 7149599148533804130, 0, 2205540801307910506482568, 0

Offset: 1

Author

R. H. Hardin Mar 12 2011

Keywords

• nonn

Comments

Column 1 of A187699

Examples

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