Some solutions for n=4
..0........0........0........0........0........0........0........0
.-1.1.....-2.2.....-2.2......1-1......1-1......0.0......2-2......1-1
..0-2.2....1.0-1....2.0-2...-1-1.2....1-1.0...-1.2-1....0.2-2....0.0.0
..1.1-2.0..1-2.1.0..0-2.2.0..0.2-2.0.-2.2.0.0..1-2.1.0.-2.0.2.0.-1.1.0.0
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