C(27,5,2) = 38
Method of Construction: covering pairs by quints, mills & mullin, jcta 49:308-322, 1988
Lower Bound: Schonheim
1 21 22 23 24
21 22 25 26 27
23 24 25 26 27
1 2 5 6 25
3 4 7 8 25
9 10 11 12 25
13 14 15 16 25
17 18 19 20 25
5 6 7 8 26
1 9 13 17 26
2 10 14 18 26
3 11 15 19 26
4 12 16 20 26
1 2 3 4 27
5 9 13 17 27
6 10 14 18 27
7 11 15 19 27
8 12 16 20 27
1 6 11 16 21
5 10 15 20 21
4 9 14 19 21
3 8 13 18 21
2 7 12 17 21
1 8 10 19 22
3 5 12 14 22
7 9 16 18 22
2 11 13 20 22
4 6 15 17 22
1 7 14 20 23
4 5 11 18 23
2 8 9 15 23
6 12 13 19 23
3 10 16 17 23
1 12 15 18 24
2 5 16 19 24
3 6 9 20 24
4 7 10 13 24
8 11 14 17 24