20 ≤ C(28,16,4) ≤ 24
Method of Construction: simple construction: multiple of smaller covering
Lower Bound: Schonheim
1 2 3 4 5 6 11 12 15 16 17 18 19 20 25 26
1 2 3 5 6 9 10 14 15 16 17 19 20 23 24 28
1 2 3 5 7 8 12 13 15 16 17 19 21 22 26 27
1 2 4 5 6 7 13 14 15 16 18 19 20 21 27 28
1 2 4 5 8 9 10 12 15 16 18 19 22 23 24 26
1 2 4 6 8 9 11 14 15 16 18 20 22 23 25 28
1 2 5 7 9 10 11 13 15 16 19 21 23 24 25 27
1 2 5 7 11 12 13 14 15 16 19 21 25 26 27 28
1 3 4 6 7 8 11 13 15 17 18 20 21 22 25 27
1 3 4 9 10 11 12 14 15 17 18 23 24 25 26 28
1 3 7 8 9 10 13 14 15 17 21 22 23 24 27 28
1 4 6 7 9 10 12 13 15 18 20 21 23 24 26 27
1 5 6 8 10 11 12 14 15 19 20 22 24 25 26 28
2 3 4 6 8 10 12 14 16 17 18 20 22 24 26 28
2 3 4 7 8 9 13 14 16 17 18 21 22 23 27 28
2 3 5 8 9 11 12 14 16 17 19 22 23 25 26 28
2 3 6 7 10 11 13 14 16 17 20 21 24 25 27 28
2 4 7 8 10 11 12 13 16 18 21 22 24 25 26 27
2 5 6 7 8 10 11 13 16 19 20 21 22 24 25 27
2 6 7 8 9 12 13 14 16 20 21 22 23 26 27 28
3 4 5 6 8 9 10 11 17 18 19 20 22 23 24 25
3 4 5 7 10 12 13 14 17 18 19 21 24 26 27 28
3 5 6 7 9 11 12 13 17 19 20 21 23 25 26 27
4 5 7 8 9 11 13 14 18 19 21 22 23 25 27 28