C(20,12,2) = 4

Created by: LJCR

Method of Construction: Multiple of (10,6,2) covering

Lower Bound: Schonheim

  1  2  3  6  7  8 11 12 13 16 17 18
  1  4  5  6  9 10 11 14 15 16 19 20
  2  3  4  7  8  9 12 13 14 17 18 19
  2  3  5  7  8 10 12 13 15 17 18 20