b21 := (1,2,3)(4,6,7)(5,8,9)(10,14,15)(11,16,17)(12,18,19)(13,20,21)(22,29,30)
     (23,31,27)(24,32,33)(25,34,35)(26,36,37)(28,38,39)(40,49,43)(41,48,50)
     (42,51,52)(44,53,54)(45,55,56)(46,57,58)(47,59,60)(61,64,65)(62,66,63);