C(28,6,2) = 28
Method of Construction: cyclic covering found by search program
Lower Bound: Schonheim
1 2 5 16 21 23
2 3 6 17 22 24
3 4 7 18 23 25
4 5 8 19 24 26
5 6 9 20 25 27
6 7 10 21 26 28
1 7 8 11 22 27
2 8 9 12 23 28
1 3 9 10 13 24
2 4 10 11 14 25
3 5 11 12 15 26
4 6 12 13 16 27
5 7 13 14 17 28
1 6 8 14 15 18
2 7 9 15 16 19
3 8 10 16 17 20
4 9 11 17 18 21
5 10 12 18 19 22
6 11 13 19 20 23
7 12 14 20 21 24
8 13 15 21 22 25
9 14 16 22 23 26
10 15 17 23 24 27
11 16 18 24 25 28
1 12 17 19 25 26
2 13 18 20 26 27
3 14 19 21 27 28
1 4 15 20 22 28