A187460 Number of (n+1)X(n+1) 0..3 arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.

192, 13726, 5098224, 3387715318, 19708386669940, 150657364854061134

Offset: 1

Author

R. H. Hardin Mar 10 2011

Keywords

• nonn

Comments

Column 3 of A187462

Examples

			Some solutions for 5X5
..0..2..2..0..1....0..2..2..0..1....0..2..2..0..1....0..2..2..0..2
..2..2..0..2..1....2..2..0..2..0....2..2..0..2..1....2..2..0..2..2
..2..0..1..0..1....2..0..3..0..2....2..0..3..0..3....2..0..2..0..1
..0..2..0..1..3....0..2..0..2..1....0..2..0..2..1....0..2..0..2..0
..1..2..1..2..3....1..2..2..1..0....1..1..3..3..3....2..1..1..3..1