sigma-orbits on X^2: [[(0, 0)], [(0, 1), (1, 2), (2, 0)], [(0, 2), (2, 1), (1, 0)], [(1, 1)], [(2, 2)]]
dim A^!_n, n=1..5: [3, 4, 3, 1, 0]
number of <r12,r23>-orbits on X^3: 6
each orbit contains a word xxy: True ; contains ztt: True
