A187668 Number of (n+1)X(n+1) 0..1 arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal.

6, 24, 112, 974, 9928, 197152, 4547688, 200947508, 10553936856, 1051895421812, 125339066655024, 28078885802576900, 7575400864257725704

Offset: 1

Author

R. H. Hardin Mar 12 2011

Keywords

• nonn

Comments

Column 1 of A187670

Examples

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