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