Some solutions for 4X4
..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
..0..0..0..4....0..0..0..0....0..0..0..0....0..0..0..4....0..0..0..4
..0..1..5..2....0..1..4..6....0..0..0..2....0..0..7..3....0..0..6..6
..0..3..7..5....0..2..7..1....2..4..6..5....0..5..4..5....0..7..2..0
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