C(25,4,2) <=50

Method of construction: simple construction: induced on c(26,5,3) covering

 1  9 17 25
 3  8 15 19
14 16 18 20
 3  9 23 24
 6 18 19 22
12 14 19 23
 2  9 13 16
 6  9 14 21
 5 15 20 23
10 13 22 23
15 16 21 22
15 17 18 24
 1  3 12 22
 5 10 19 25
 7 11 16 23
 3  7 10 18
 3 17 20 21
 7 13 17 19
 4 11 18 25
 4  9 10 15
 2 19 21 24
 2 11 12 15
 4  6 17 23
 2 10 14 17
 1  2 18 23
 8 11 17 22
 1  5  8 14
 9 11 19 20
 4  8 13 20
 1  6 13 15
 7 14 15 25
 4  7 12 21
 1  7 20 24
 2  3  4  5
 2 20 22 25
 5  6 11 24
 8  9 12 18
12 13 24 25
 5 12 16 17
 3  6 16 25
 3 11 13 14
 1  4 16 19
 6 10 12 20
 8 21 23 25
 8 10 16 24
 2  6  7  8
 4 14 22 24
 1 10 11 21
 5 13 18 21
 5  7  9 22