C(15,6,2) = 10

Method of Construction: lex covering

Lower Bound: Handbook of Combinatorial Designs section on coverings

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