A187630 Number of (n+1)X(n+1) 0..2 arrays with the array of 2X2 subblock determinants antisymmetric under horizontal and vertical reflection and each non-centerline 2X2 subblock nonsingular.

31, 446, 1648, 557382, 672698, 21411605018, 22329564088

Offset: 1

Author

R. H. Hardin Mar 12 2011

Keywords

• nonn

Comments

Column 2 of A187633

Examples

			Some solutions for 4X4
..2..0..0..2....2..1..2..0....1..1..1..0....1..2..2..1....0..1..2..1
..1..1..1..0....2..0..0..1....2..0..0..2....2..2..2..2....2..0..0..1
..2..2..2..0....1..0..0..1....2..0..0..1....2..2..2..2....1..0..0..1
..1..0..0..1....2..2..2..2....1..1..2..0....1..2..2..1....1..2..2..1