lower bound = 38

C(27,5,2) = 38

Method of Construction: covering pairs by quints, mills & mullin, jcta 49:308-322, 1988

Lower Bound: Schonheim

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