A215871 Number of permutations of 0..floor((3*n-2)/2) on odd squares of an 3Xn array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.

1, 1, 1, 2, 4, 12, 29, 110, 290, 1274, 3532, 17136, 49100, 255816, 750325, 4124406, 12310294, 70549050, 213446666, 1264752060, 3868253164, 23555382240, 72686739116, 452806924752

Offset: 1

Author

R. H. Hardin Aug 25 2012

Keywords

• nonn

Comments

Row 3 of A215870

Examples

			Some solutions for n=6
..x..0..x..2..x..3....x..0..x..2..x..4....x..0..x..1..x..4....x..0..x..1..x..4
..1..x..4..x..6..x....1..x..3..x..6..x....2..x..3..x..5..x....2..x..3..x..6..x
..x..5..x..7..x..8....x..5..x..7..x..8....x..6..x..7..x..8....x..5..x..7..x..8