28 ≤ C(13,7,4) ≤ 30
Method of Construction: nurmela and ostergard simulated annealing cover
Lower Bound: Schonheim
1 2 5 6 7 8 9
1 3 4 5 6 8 10
2 3 6 7 8 9 10
2 3 4 5 8 9 11
1 3 5 7 8 10 11
1 2 4 8 9 10 11
1 2 3 5 7 10 12
1 3 4 5 9 10 12
1 2 4 5 6 11 12
1 3 6 7 9 11 12
2 6 7 8 9 11 12
4 6 7 8 9 11 12
2 3 4 6 10 11 12
5 6 7 9 10 11 12
3 4 5 6 7 9 13
1 2 3 5 6 10 13
1 4 6 7 9 10 13
1 2 3 4 7 11 13
2 4 7 8 9 11 13
2 4 5 7 10 11 13
1 3 5 9 10 11 13
1 4 5 7 8 12 13
2 4 6 7 8 12 13
1 2 3 8 9 12 13
3 4 7 8 10 12 13
2 5 8 9 10 12 13
3 5 6 8 11 12 13
2 4 6 9 11 12 13
6 7 8 9 11 12 13
1 6 8 10 11 12 13