C(26,9,2) = 12

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

Lower Bound: Schonheim

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