C(15,3,2) <=35

Method of construction: lex covering

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