Some solutions with the first block increasing clockwise for 3 X 7:
..1..2..0..1..2..0..1....1..2..3..1..2..1..2....2..5..4..3..4..1..2
..4..3..5..4..3..5..4....0..5..4..0..4..0..4....1..0..1..2..5..0..5
..0..1..0..1..2..0..2....1..2..3..1..3..1..3....3..5..4..3..4..2..3
...
...R..L..R..R..L..R.......R..R..L..R..L..R.......R..L..L..R..L..R...
...L..R..L..L..R..L.......L..L..R..L..R..L.......L..R..R..L..R..L...
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