elements of order 7 among companion matrices with det 1: 2
involutions scanned (normalised v, all w with w.v = 1): 16093
orders of <x,y> with x^2 = (xy)^3 = y^7 = 1: {168: 133}
PSL(2,7) found: order 168 < M = 29040; point orbits [21, 28, 84]
