31 ≤ C(18,7,3) ≤ 32

Created by: Franco Atzeni

Method of Construction: cyclic covering found by search program

Lower Bound: Schonheim

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