C(17,11,2) <=4

Method of construction: lex covering

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