xn 4  pxn 16  palbits 7 ppalbits 128
  M #      0 = 1000 0000 0000 0001   :   2
    Members:
    ....
    abcd

sigmas with   2 members: 1
  M #      1 = 1100 0000 0000 0011   :   4
    Members:
    ....
    a...
    .bcd
    abcd

  M #      2 = 1010 0000 0000 0101   :   4
    Members:
    ....
    .b..
    a.cd
    abcd

  M #      3 = 1001 0000 0000 1001   :   4
    Members:
    ....
    ab..
    ..cd
    abcd

  M #      4 = 1000 1000 0001 0001   :   4
    Members:
    ....
    ..c.
    ab.d
    abcd

  M #      5 = 1000 0100 0010 0001   :   4
    Members:
    ....
    a.c.
    .b.d
    abcd

  M #      6 = 1000 0010 0100 0001   :   4
    Members:
    ....
    .bc.
    a..d
    abcd

  M #      7 = 1000 0001 1000 0001   :   4
    Members:
    ....
    abc.
    ...d
    abcd

sigmas with   4 members: 7
  M #      8 = 1111 0000 0000 1111   :   8
    Members:
    ....
    a...
    .b..
    ab..
    ..cd
    a.cd
    .bcd
    abcd

  M #      9 = 1100 1100 0011 0011   :   8
    Members:
    ....
    a...
    ..c.
    a.c.
    .b.d
    ab.d
    .bcd
    abcd

  M #     10 = 1010 1010 0101 0101   :   8
    Members:
    ....
    .b..
    ..c.
    .bc.
    a..d
    ab.d
    a.cd
    abcd

  M #     11 = 1001 1001 1001 1001   :   8
    Members:
    ....
    ab..
    ..c.
    abc.
    ...d
    ab.d
    ..cd
    abcd

  M #     12 = 1010 0101 1010 0101   :   8
    Members:
    ....
    .b..
    a.c.
    abc.
    ...d
    .b.d
    a.cd
    abcd

  M #     13 = 1100 0011 1100 0011   :   8
    Members:
    ....
    a...
    .bc.
    abc.
    ...d
    a..d
    .bcd
    abcd

sigmas with   8 members: 6
  M #     14 = 1111 1111 1111 1111   :  16
    Members:
    ....
    a...
    .b..
    ab..
    ..c.
    a.c.
    .bc.
    abc.
    ...d
    a..d
    .b.d
    ab.d
    ..cd
    a.cd
    .bcd
    abcd

sigmas with  16 members: 1

n = 4, sigma count 15.