a11 := (2,3)(4,5)(6,8)(7,10)(9,13)(11,15)(12,17)(14,20)(16,23)(18,25)(19,27)
     (24,33)(26,36)(28,38)(29,40)(30,42)(31,43)(32,45)(34,48)(35,49)(37,51)
     (39,53)(41,54)(44,58)(46,60)(47,62)(52,63)(55,68)(56,69)(57,70)(61,65)
     (64,72)(66,74)(67,76)(73,78);