b21 := (1,2,5,10,18,28,41,34,22,13,7,3)(4,8,14,23,35,48,56,42,29,19,11,6)(9,15,
     24,36,49,62,57,43,30,20,12,16)(17,25,37,50,63,69,58,44,32,21,31,26)(27,
     38,51,64,73,70,59,46,33,45,52,39)(40,53,65,74,77,72,61,47,60,71,66,54)
     (55,67,75,78,76,68);