C(18,13,4) = 9

Method of Construction: dynamic programming covering

Lower Bound: Schonheim

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