Some solutions with upper left block zero for 3X7
..0..0..2..0..0..0..3....0..0..0..0..1..0..0....0..0..0..0..1..0..2
..0..0..2..2..0..0..0....0..0..3..2..0..0..1....0..0..1..2..0..0..1
..2..0..1..0..1..0..0....2..0..1..0..2..0..2....1..0..3..0..3..0..0
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