20 ≤ C(21,12,4) ≤ 25

Created by: Jan de Heer

Method of Construction: Ininuga (by Uros Boltin)

Lower Bound: Schonheim

  1  2  3  4  5  6  7  8  9 13 19 21
  1  2  3  4  5  6  9 11 15 16 20 21
  1  2  3  4  5  6 10 12 14 17 18 21
  1  2  3  4  5  7  8  9 10 13 18 20
  1  2  3  4  5  8  9 12 14 17 19 20
  1  2  3  4  5  8 10 11 15 16 18 19
  1  2  3  4  6  7  9 12 15 16 18 19
  1  2  3  4  6  7 10 11 14 17 19 20
  1  2  3  4  6  8  9 11 12 13 18 20
  1  2  3  4  7  8  9 11 14 17 18 21
  1  2  3  4  7  8 10 12 15 16 20 21
  1  2  3  4  8  9 10 11 12 13 19 21
  1  2  3  5  7 11 12 13 14 15 16 17
  1  2  4 13 14 15 16 17 18 19 20 21
  1  3  4  6  8  9 10 13 14 15 16 17
  1  3  9 13 14 15 16 17 18 19 20 21
  2  5  6  7  8  9 10 13 14 15 16 17
  4  5  7  8  9 11 12 13 14 15 16 17
  5  6  7  8 10 11 12 13 14 15 18 21
  5  6  7  8 10 11 12 13 14 15 19 20
  5  6  7  8 10 11 12 13 16 17 18 19
  5  6  7  8 10 11 12 13 16 17 20 21
  5  6  9 10 11 12 15 17 18 19 20 21
  5  7  8  9 14 15 16 17 18 19 20 21
  6  7  9 10 11 12 14 16 18 19 20 21