lower bound = 12

C(9,5,3) = 12

Method of Construction: lex covering

Lower Bound: Theorem 2.1 of Mills and Mullin; r=2

  1  2  3  4  5
  1  2  6  7  8
  3  4  6  7  9
  1  3  5  8  9
  2  4  5  6  8
  2  4  5  7  9
  1  3  5  6  7
  1  4  7  8  9
  2  3  6  8  9
  1  2  4  6  9
  2  3  4  7  8
  5  6  7  8  9