lower bound = 20

C(16,4,2) = 20

Method of Construction: simple construction: induced on c(17,5,3) covering

Lower Bound: Schonheim

  2  3  7  9
  6  7  8 10
  1  7 15 16
  1  3 12 14
  1  2  6 13
  1  9 10 11
  2  4 10 12
  1  4  5  8
 10 13 14 16
  8  9 12 16
  3  8 11 13
  2  5 11 16
  5  7 12 13
  3  4  6 16
  5  6  9 14
  2  8 14 15
  4  9 13 15
  6 11 12 15
  4  7 11 14
  3  5 10 15