C(13,7,2) = 6
Method of Construction: lex covering
Lower Bound: Bounds for fixed number of blocks
1 2 3 4 5 6 7 1 8 9 10 11 12 13 2 3 4 5 8 9 10 2 3 4 5 11 12 13 6 7 8 9 10 11 12 1 2 3 4 6 7 13