C(9,4,2) = 8
Method of Construction: lex covering
Lower Bound: Horsley, Theorem 1, r=3, d=1
1 2 3 4 1 5 6 7 2 5 8 9 3 4 6 8 3 4 7 9 1 2 6 9 1 2 7 8 1 3 4 5