The a(2) = 11 matrices are:
[1 0 0 0] [1 1 0 0] [1 1 1 0] [1 1 0 0] [1 1 0 0]
[1 0 0 0] [1 0 0 0] [1 0 0 0] [1 0 1 0] [1 0 0 0]
[0 1 0 0] [0 1 0 0] [0 1 0 0] [0 1 0 0] [0 1 0 0]
[0 1 0 0] [0 0 1 0] [0 0 1 0] [0 0 1 0] [0 0 1 1]
[0 0 1 0] [0 0 1 0] [0 0 0 1] [0 0 0 1] [0 0 1 0]
[0 0 1 0] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1]
[0 0 0 1] [0 0 0 1]
[0 0 0 1]
.
[1 1 1 1] [1 1 1 0] [1 1 0 0] [1 1 0 0] [1 1 0 1] [1 1 0 0]
[1 0 0 0] [1 0 0 1] [1 0 1 0] [1 0 1 0] [1 0 1 0] [1 0 1 0]
[0 1 0 0] [0 1 0 0] [0 1 1 0] [0 1 0 1] [0 1 1 0] [0 1 0 1]
[0 0 1 0] [0 0 1 0] [0 0 0 1] [0 0 1 0] [0 0 0 1] [0 0 1 1]
[0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1]
.
A set system corresponding to the first of these is {{1,2}, {3,4}, {5,6}, {7,8}}.
|