C(31,8,2) = 20

Method of Construction: simple construction: deleted element from c(v+1,k,t) covering

Lower Bound: Schonheim

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