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