Number of potential flows in n X n array with integer velocities in -9..9, i.e., number of n X n arrays with adjacent elements differing by no more than 9, counting arrays differing by a constant only once.

A068756

Number of potential flows in n X n array with integer velocities in -9..9, i.e., number of n X n arrays with adjacent elements differing by no more than 9, counting arrays differing by a constant only once.