a21 := (1,3,6,11)(2,4,8,14)(5,9,16,25)(7,12,20,31)(10,17,27,41)(13,21,33,50)
     (15,23,36,55)(18,28,43,64)(19,29,45,67)(22,34,52,76)(24,37,57,83)(26,39,
     60,87)(30,46,69,98)(32,48,72,102)(35,53,78,109)(38,58,84,118)(40,61,49,
     73)(42,51)(44,65,93,129)(47,70,99,138)(54,79,111,152)(56,81,114,157)(59,
     85,120,164)(62,89,124,169)(63,90,82,115)(66,94,131,178)(68,96,134,183)
     (71,100,140,190)(74,104,144,195)(75,105,97,135)(77,107,148,201)(80,112,
     154,168)(86,121,153,207)(88,122,166,222)(91,126,172,228)(92,127,174,231)
     (95,132,180,194)(101,141,179,237)(103,142,192,252)(106,146,198,258)(108,
     149,203,265)(110,150,205,267)(113,155,209,271)(116,159,214,278)(117,160,
     151,206)(119,162,218,283)(123,167,224,289)(125,170,223,287)(128,175,233,
     300)(130,176,235,302)(133,181,239,306)(136,185,244,312)(137,186,177,236)
     (139,188,248,317)(143,193,254,322)(145,196,253,320)(147,199,260,329)(156,
     210,273,343)(158,212,275,346)(161,216,280,353)(163,219)(165,220)(171,227,
     268,338)(173,229,295,369)(182,240,308,383)(184,242,310,386)(187,246,314,
     392)(189,249)(191,250)(197,257,303,378)(200,261)(202,263,332,412)(204,
     266,336,416)(208,270,264,333)(211,274,345,423)(213,276,347,425)(215,279,
     351,430)(217,281,355,434)(221,285,360,440)(225,290,363,443)(226,291,318,
     397)(230,296)(232,298,372,453)(234,301,376,456)(238,305,299,373)(241,309,
     385,462)(243,286,361,441)(245,313,390,468)(247,315,394,472)(251,319,399,
     478)(255,323,401,480)(256,324,284,358)(259,327,406,340)(262,331,411,488)
     (269,339,418,497)(272,341,307,381)(277,348,342,420)(282,356,436,510)(288,
     362,344,422)(292,365,445,518)(293,366,429,447)(294,367,448,380)(297,371,
     452,523)(304,379,446,519)(311,387,382,459)(316,395,474,542)(321,400,384,
     461)(325,403,482,489)(326,404,467,405)(328,407,483,550)(330,409,485,551)
     (334,413,374,454)(335,414,492,479)(337,417,496,563)(349,427,388,465)(350,
     428,504,572)(354,432,476,484)(357,437,511,579)(359,439,514,582)(364,444,
     516,585)(368,415,493,559)(370,450,520,586)(375,455,526,442)(377,457,529,
     594)(389,466,536,602)(393,470,438,512)(396,475,543,609)(398,477,545,612)
     (402,481,547,614)(410,486,553,618)(419,498,565,625)(421,499,566,620)(424,
     500,567,627)(426,501,569,629)(431,505,509,506)(433,507,575,534)(435,487,
     554,549)(451,521,588,636)(458,530,595,639)(460,531,596,637)(463,532,597,
     641)(464,533,599,643)(469,537,541,538)(471,539,605,502)(473,522,589,558)
     (490,556,513,580)(491,557)(494,560,622,651)(495,561,573,624)(503,570,581,
     578)(508,576,584,632)(515,583,630,635)(517,548)(524,590,544,610)(525,591)
     (527,555,619,649)(528,592,603,638)(535,600,611,608)(540,606,613,645)(546,
     564,623,617)(552,616,648,598)(562,604,621,650)(568,587,634,654)(571,628,
     601,642)(574,615,647,593)(577,631,653,657)(607,644,652,656)(626,633,640,
     646)(655,658)(659,660);