A068748 Number of potential flows in n X n array with integer velocities in -1..1, i.e., number of n X n arrays with adjacent elements differing by no more than 1, counting arrays differing by a constant only once.
1, 19, 1665, 690437, 1366395515, 12961320464027, 590771311004409091, 129585582154154757804255, 136932044780329080616264070553, 697547669137459516115242710064880165
Offset: 1