C(19,12,3) = 9

Method of Construction: dynamic programming covering

Lower Bound: Handbook of Combinatorial Designs section on coverings

  1  2  3  4  5  6  7  8  9 10 11 12
  1  2  3  4  5  6  7  8  9 10 13 14
  1  2  3  4  5  6  7  8  9 10 15 16
  1  2  3  4  5  6  7  8  9 10 17 18
  1  2  3  4  5  6  7  8  9 10 14 19
  1  2  3 11 12 13 14 15 16 17 18 19
  4  5  6 11 12 13 14 15 16 17 18 19
  7  8  9 11 12 13 14 15 16 17 18 19
  2  3 10 11 12 13 14 15 16 17 18 19