b21 := (1,3,6)(2,4,8)(5,9,13)(7,10,15)(11,16,22)(12,17,24)(14,19,27)(18,25,33)
     (20,28,37)(23,30,40)(26,34,45)(29,38,49)(31,41,53)(32,42,55)(35,46,60)
     (36,47,61)(39,50,65)(43,56,72)(44,57,74)(48,62,80)(51,66,85)(52,67,87)
     (54,69,90)(58,75,97)(59,76,99)(63,81,105)(64,82,107)(68,88,114)(70,91,
     118)(71,92,120)(73,94,123)(77,100,130)(78,101,132)(79,102,134)(83,108,
     141)(84,109,143)(86,111,146)(89,115,150)(93,121,157)(95,124,161)(96,125,
     163)(98,127,166)(103,135,174)(104,136,176)(106,138,179)(110,144,186)(112,
     147,190)(116,151,195)(117,152,196)(119,154,198)(122,158,203)(126,164,210)
     (128,167,214)(129,168,216)(131,170,218)(133,171,219)(137,177,226)(139,
     180,229)(140,181,231)(142,183,153)(145,187,169)(148,191,241)(149,192,243)
     (155,199,250)(156,200,252)(159,204,257)(160,205,259)(162,207,262)(165,
     211,267)(172,220,275)(173,221,277)(175,223,280)(182,232,290)(184,234,293)
     (185,235,295)(188,237,298)(189,238,300)(193,244,307)(197,247,310)(201,
     253,317)(202,254,319)(206,260,325)(208,263,329)(209,264,331)(212,268,336)
     (213,269,338)(217,271,341)(222,278,347)(224,281,351)(225,282,353)(227,
     284,356)(228,285,358)(230,287,361)(233,291,366)(236,296,372)(239,301,378)
     (240,302,379)(242,304,349)(245,308,384)(246,255,320)(248,311,387)(249,
     312,389)(251,314,392)(256,321,399)(258,323,401)(261,326,405)(265,332,411)
     (266,333,413)(270,339,419)(272,342,423)(273,343,425)(274,344,427)(276,
     306,382)(279,348,432)(283,354,437)(286,359,442)(288,362,446)(289,363,448)
     (292,367,453)(294,369,455)(297,373,459)(299,375,462)(303,380,468)(305,
     381,470)(309,370,456)(313,390,476)(315,393,480)(316,394,482)(318,396,485)
     (322,360,443)(324,402,490)(327,406,494)(328,407,496)(330,409,498)(334,
     414,504)(335,415,506)(337,417,508)(340,420,512)(345,428,517)(346,429,503)
     (350,433,519)(352,435,473)(355,424,514)(357,439,526)(364,449,536)(365,
     450,537)(368,454,540)(371,431,421)(374,460,546)(376,463,550)(377,464,552)
     (383,472,559)(385,391,477)(386,474,561)(388,475,563)(395,483,571)(397,
     486,573)(398,479,567)(400,488,416)(403,491,579)(404,492,581)(408,497,426)
     (410,499,565)(412,501,588)(418,509,592)(422,513,596)(430,518,601)(434,
     520,451)(436,522,603)(438,524,562)(440,527,535)(441,528,605)(444,531,608)
     (445,532,610)(447,534,613)(452,538,616)(457,543,621)(458,544,623)(461,
     547,626)(465,553,631)(466,487,574)(467,554,633)(469,556,636)(471,557,577)
     (478,566,645)(481,569,649)(484,572,652)(489,576,655)(493,568,647)(495,
     583,651)(500,586,614)(502,589,664)(505,560,640)(507,591,595)(510,593,521)
     (511,594,669)(515,598,620)(516,599,671)(525,551,629)(530,606,570)(533,
     611,646)(541,618,666)(542,619,685)(545,624,689)(548,627,575)(555,634,696)
     (558,638,700)(564,643,703)(578,656,709)(582,659,607)(584,660,650)(585,
     661,678)(587,628,692)(590,665,684)(597,630,693)(600,672,721)(604,674,719)
     (612,679,725)(615,681,727)(617,682,699)(622,687,680)(625,690,733)(632,
     694,637)(635,697,738)(639,701,739)(641,691,734)(642,668,717)(644,704,711)
     (648,657,710)(654,707,743)(662,683,720)(663,714,745)(667,716,746)(670,
     718,748)(673,722,698)(675,723,751)(677,724,752)(686,730,715)(688,732,756)
     (695,736,702)(706,741,713)(708,735,731)(726,753,729)(728,744,754)(737,
     757,759)(742,749,747);