C(15,12,2) = 3

Created by LJCR

Method of Construction: Multiple of (5,4,2) covering

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