1:  0 00 000
       2:  0 00 001
       3:  0 00 011
       4:  0 00 111
       5:  0 01 010
       6:  0 01 011
       7:  0 01 100
       8:  0 01 110
       9:  0 01 111
      10:  0 11 111
      11:  1 10 100
      12:  1 10 101
      13:  1 10 111
      14:  1 11 110
      15:  1 11 111