n=6: labelled racks 36538, isomorphism classes 353  (20.3s)
  B3-classes (= twist classes): 338; groups with >1 rack: 14, sizes [2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3]
  unordered twist pairs of non-isomorphic racks: 16; all twists verified and non-isomorphic: True; dual pairs among them: 1; pairs of quandles: 5
  non-self-dual racks: 2; of these not twist-related to their dual: 0
  time 21.2s
