C(17,7,2) <=9

Method of construction: random greedy covering

 1  2  4  7 11 15 16
 3  8  9 12 13 14 17
 1  2  3  5  6 10 13
 6  8 10 11 12 16 17
 4  6  7  9 10 14 15
 4  5  7  8 12 15 17
 2  3  5  9 11 14 16
 1  2  8  9 12 14 17
 3  4  7 11 13 15 16