“…We can then obtain the result for B n by the usual birational equivalence. In fact it suffices to compute the degree in ζ of H h n,1 − H h n,2 where H n,1 H n,2 = h n ζ,ρ (1) and H h n,j is the homogenised version of H n,j . The zero set of H h n,1 − H h n,2 is the union of sets A d for d dividing n. We claim that the degree is 2 n − 1.…”