lower bound = 13

C(13,7,3) = 13

Method of Construction: cyclic covering found by a search program

Lower Bound: Handbook of Combinatorial Designs section on coverings

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