C(27,4,2) = 61

Method of Construction: simple construction: induced on c(28,5,3) covering

Lower Bound: Schonheim

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