A187458 Number of (n+1)X(n+1) 0..1 arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.

6, 26, 144, 1272, 15192, 286392, 7648032, 314011868, 18986004296, 1725663296600, 237096836118080, 48071903199959400, 15027587384189632928, 6819730931931151055960, 4852231403635188536789728

Offset: 1

Author

R. H. Hardin Mar 10 2011

Keywords

• nonn

Comments

Column 1 of A187462

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..18