b21 := (1,2,3)(4,6,7)(5,8,9)(10,14,15)(11,16,17)(12,18,19)(13,20,21)(22,30,31)
     (23,32,28)(24,33,34)(25,35,36)(26,37,38)(27,39,40)(29,41,42)(43,56,57)
     (44,58,59)(45,60,61)(46,62,63)(47,64,65)(48,66,67)(49,68,69)(50,70,71)
     (51,72,73)(52,74,75)(53,76,77)(54,78,79)(55,80,81)(82,98,99)(83,96,100)
     (84,101,102)(85,103,104)(86,105,106)(87,107,108)(88,109,110)(89,111,112)
     (90,113,114)(91,115,116)(92,117,118)(93,119,120)(94,121,122)(95,123,124)
     (97,125,126)(127,144,143)(128,145,146)(129,133,138)(130,147,148)(131,149,
     150)(132,151,139)(134,152,153)(135,154,155)(136,156,157)(137,158,159)
     (140,160,161)(141,162,163)(142,164,165)(166,168,167)(169,170,171);