a21 := (1,3,6,10,16,26,5)(2,4,8,13,21,32,45)(7,11,18,28,41,58,85)(9,14,23,34,
     49,70,101)(12,19,29,42,60,87,59)(15,24,35,50,72,103,140)(17,27,39,55,81,
     114,153)(20,30,43,62,90,124,163)(22,33,47,67,96,131,172)(25,36,52,75,69,
     99,134)(31,44,63,91,125,164,207)(37,53,77,71,102,138,171)(38,54,79,111,
     149,191,239)(40,56,82,116,156,197,244)(46,65,93,128,168,214,257)(48,68,
     98,133,137,178,224)(51,73,105,95,129,169,216)(57,83,117,121,159,201,247)
     (61,88,122,160,202,206,250)(64,92,104,141,181,228,241)(66,94,84,118,157,
     199,246)(74,106,142,182,229,139,179)(76,107,144,184,231,269,119)(78,109,
     146,186,234,270,301)(80,112,150,193,200,143,183)(86,120,158,180,226,266,
     195)(89,123,162,205,227,267,299)(97,132,174,221,262,294,155)(100,135,177,
     222,263,295,320)(108,145,185,232,213,256,176)(110,147,188,236,273,173,
     219)(113,151,194,242,277,306,329)(115,154,196,243,278,307,330)(126,165,
     209,252,286,152,136)(127,166,211,254,287,204,249)(130,170,217,260,291,
     317,340)(148,189,237,275,305,328,336)(161,203,248,282,311,334,175)(167,
     212,255,289,316,210,253)(187,235,272,304,327,353,362)(190,238,225,208,
     251,285,314)(192,240,276,284,313,337,233)(198,245,280,309,332,259,218)
     (215,258,290,230,268,300,274)(220,261,292,318,338,355,364)(223,264,296,
     321,344,359,368)(265,297,322,345,350,323,346)(271,302,325,349,361,370,
     374)(279,308,331,288,315,339,298)(281,310,333,303,326,351,341)(283,312,
     335,357,366,354,363)(293,319,342,343,352,324,347)(348,360,369,373,376,
     377,378)(356,365,372,375,371,358,367);