16 ≤ C(31,9,2) ≤ 17

Created by: Rade Belic and Jan de Heer

Lower Bound: Horsley, Theorem 1, r=4, d=2

  1  2  3  4  5  6 19 20 21
  1  2  7  8  9 10 22 23 24
  1  2 11 12 13 14 25 26 27
  1  2 15 16 17 18 28 29 31
  1  2 15 16 17 18 28 30 31
  3  4  7  8 13 14 25 29 30
  3  4  9 10 11 12 26 28 31
  3  4  9 10 17 18 24 25 27
  3  4 11 12 15 16 22 23 24
  5  6  7  8 13 14 24 28 31
  5  6  7  8 15 16 25 26 27
  5  6  9 10 11 12 22 29 30
  5  6 13 14 17 18 22 23 26
  7  8 11 12 17 18 19 20 21
  9 10 13 14 15 16 19 20 21
 19 20 21 22 23 25 27 28 31
 19 20 21 23 24 26 27 29 30