A193609 Number of n X n symmetric 0..2 arrays with no element equal to the sum mod 3 of all its horizontal and vertical neighbors.

2, 6, 64, 1026, 32832, 2097152, 268435456, 68719348224, 35184372089856, 36028797018963968, 73786976297388343296

Offset: 1

Author

R. H. Hardin Jul 31 2011

Keywords

• nonn

Examples

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