Some solutions for n=3
..0..4..0....0..4..0....0..4..0....0..4..0....0..4..0....0..4..0....0..4..0
..0..4..6....0..2..6....6..4..6....0..4..5....0..4..6....0..2..3....0..4..0
..0..4..0....3..2..0....6..7..5....5..4..6....5..4..5....3..7..3....6..2..3
..0..4..5....0..2..3....6..4..0....6..7..5....5..1..0....3..1..0....6..2..0
..6..4..5....6..7..3....0..2..6....5..1..5....3..2..6....3..1..3....6..2..0
Vertex neighbors:
0 -> 1 2 4
1 -> 0 3 5
2 -> 0 3 6
3 -> 1 2 7
4 -> 0 5 6
5 -> 1 4 7
6 -> 2 4 7
7 -> 3 5 6
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