Number of (n+1) X (n+1) 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to the number of counterclockwise edge increases.

A209512

Number of (n+1) X (n+1) 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to the number of counterclockwise edge increases.