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