For n=2, there are 6 patterns to color the vertices of the square:
..1..1....1..1....1..1....1..0....1..0....0..0
..1..1....1..0....0..0....0..1....0..0....0..0
For example, the next pattern is regarded as the same with the 3rd one above:
..1..0
..1..0
