n=6: 1905 reachable points with |B|<=60, 663 direction classes
distinct patterns: class | (preclosed length / shortest , reduced factor) ... | unreduced factor tuples -> number of direction classes
  class even | 1.00000:x1  2.00000:x1 | {(1, 1): 44} | n among reduced factors: False
  class even | 1.00000:x3  2.00000:x1 | {(3, 1): 122} | n among reduced factors: False
  class odd  | 1.00000:x1 | {(3,): 374, (1,): 123} | n among reduced factors: False
longest closed trajectory met: 414 bounces
direction classes with a reduced factor equal to n: 0 of 663
Theorem 7(a) on these direction classes: every (unreduced) factor divides n/2: True (829 bands)
exact decisions: 40812, time 2.1s
