A229438 Number of n X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing.

3, 7, 22, 109, 753, 6374, 62205, 676983, 8026548, 101907085, 1368004992, 19233435438, 281169127711, 4249797119751, 66116288446463

Offset: 1

Author

R. H. Hardin Sep 23 2013

Keywords

• nonn

Comments

Diagonal of A229445

Examples

			Some solutions for n=4
..0..2..2..2....0..2..2..2....0..2..2..2....0..0..0..0....1..1..1..1
..1..0..2..2....1..0..0..2....1..0..0..2....1..1..1..1....2..2..2..2
..1..1..0..0....2..1..1..0....1..1..1..0....1..1..1..1....2..2..2..2
..2..1..0..0....2..1..1..1....2..1..1..0....2..2..2..2....2..2..2..2