16 ≤ C(28,13,3) ≤ 19

Method of Construction: simple construction: induced on c(29,14,4) covering

Lower Bound: Schonheim

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