b11 := (1,2)(3,5)(4,7)(6,10)(8,12)(9,13)(11,16)(14,17)(15,20)(18,23)(19,25)(21,
     28)(22,29)(24,31)(26,32)(27,33)(30,36)(34,39)(35,40)(37,42)(38,44)(41,46)
     (43,47)(45,48);