C(14,4,2) <=18

Method of construction: lex covering

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