b21 := (1,3,6,11)(2,4,8,14)(5,9,16,25)(7,12,20,31)(10,17,27,41)(13,21,33,50)
     (15,23,36,54)(18,28,43,44)(19,29,45,65)(22,34,52,35)(24,37,56,79)(26,39,
     59,82)(30,46,67,93)(32,48,70,97)(38,57,81,58)(40,60,84,116)(42,62,87,120)
     (47,68,95,69)(49,71,99,134)(51,73,102,137)(53,75,105,142)(55,77,108,146)
     (61,85,118,86)(63,88,122,161)(64,89)(66,91,126,166)(72,100,135,101)(74,
     103,139,183)(76,106,144,107)(78,109,147,191)(80,111,150,194)(83,114,112,
     151)(90,124,164,125)(92,127,168,212)(94,129,171,172)(96,130,173,217)(98,
     132,176,221)(104,140,184,229)(110,148,193,149)(113,152)(115,153,133,177)
     (117,155,198,243)(119,157,201,246)(121,159,204,250)(123,162,206,253)(128,
     169,214,170)(131,174,219,175)(136,180,225,275)(138,182,228,279)(141,185,
     154,197)(143,187,232,284)(145,189,235,288)(156,199)(158,202,248,203)(160,
     205,190,236)(163,207,254,305)(165,209,257,310)(167,211,260,192)(178,223,
     272,179)(181,226,277,227)(186,230,282,231)(188,233,285,340)(195,239,293,
     294)(196,240,295,350)(200,244,218,267)(208,255,307,363)(210,258,312,259)
     (213,262,316,370)(215,264,241,296)(216,265,320,375)(220,268,324,379)(222,
     270,319,351)(224,273,328,382)(234,286,341,395)(237,290,345,346)(238,291,
     347,292)(242,280,335,323)(245,297,353,405)(247,299,356,408)(249,256,308,
     364)(251,302)(252,303,359,412)(261,314,301,315)(263,317,372,422)(266,321,
     377,322)(269,325,381,326)(271,327,374,424)(274,329,339,338)(276,331,386,
     435)(278,333,389,437)(281,318,373,423)(283,337,336,392)(287,342,397,365)
     (289,334,390,358)(298,354,406,355)(300,357,410,309)(304,360,413,428)(306,
     362,361,414)(311,366,416,400)(313,368,407,443)(330,384,433,385)(332,387)
     (343,398,442,391)(344,399,444,459)(348,402,447,486)(349,403,449,489)(352,
     404,450,491)(367,417,460,499)(369,415,457,496)(371,420,464,502)(376,426,
     470,506)(378,427,472,456)(380,429,473,498)(383,432,476,479)(388,436,434,
     478)(394,439,480,509)(396,441,483,513)(401,445,458,497)(409,454,421,465)
     (411,455,495,438)(418,461,500,523)(419,462,501,463)(425,468,505,469)(430,
     474,452,467)(431,451,492,475)(440,481,511,482)(446,485,515,533)(448,487,
     516,535)(453,493,520,494)(466,504,526,477)(471,484,514,524)(488,517,527,
     542)(490,518,538,549)(503,525)(507,508,529,543)(510,531,545,512)(519,539,
     550,557)(521,540,544,530)(522,541,551,558)(528,536,548,537)(534,546,554,
     559)(547,555,553,556);