b21 := (1,3,5)(2,4,7)(6,9,12)(8,11,15)(10,13,18)(14,19,25)(16,21,20)(17,22,26)
     (23,27,24)(28,30,33)(29,31,35)(32,36,41)(34,38,44)(37,42,43)(39,45,40)
     (46,50,55)(47,51,57)(48,52,59)(49,53,61)(54,62,71)(56,64,74)(58,66,77)
     (60,68,80)(63,72,73)(65,75,87)(67,78,79)(69,81,93)(70,82,94)(76,88,99)
     (83,95,106)(84,96,108)(85,97,110)(86,98,112)(89,100,115)(90,101,117)(91,
     102,119)(92,103,114)(104,113,129)(105,121,137)(107,123,140)(109,125,143)
     (111,127,146)(116,131,151)(118,133,154)(120,135,157)(122,138,139)(124,
     141,162)(126,144,145)(128,147,167)(130,149,150)(132,152,171)(134,155,156)
     (136,158,176)(142,163,179)(148,168,175)(153,172,187)(159,166,182)(160,
     177,192)(161,178,194)(164,180,197)(165,181,199)(169,185,203)(170,186,204)
     (173,188,207)(174,189,208)(183,201,184)(190,209,226)(191,210,228)(193,
     212,231)(195,214,234)(196,215,236)(198,217,239)(200,219,242)(202,221,244)
     (205,223,247)(206,224,249)(211,229,230)(213,232,256)(216,237,238)(218,
     240,263)(220,243,266)(222,245,269)(225,250,275)(227,252,277)(233,257,279)
     (235,259,258)(241,264,283)(246,270,287)(248,272,271)(251,276,265)(253,
     262,282)(254,261,281)(255,278,292)(260,280,293)(267,285,298)(268,286,300)
     (273,288,301)(274,284,296)(289,302,306)(290,299,308)(291,303,311)(294,
     305,310)(295,297,307)(304,312,313)(309,314,315);