Let n be a positive integer and f (x) := x 2 n + 1. In this paper, we study orders of primes dividing products of the form P m,n := f (1)f (2) · · · f (m). We prove that if m > max{10 12 , 4 n+1 }, then there exists a prime divisor p of P m,n such that ord p (P m,n ) ≤ n · 2 n−1 . For n = 2, we establish that for every positive integer m, there exists a prime divisor p of P m,2 such that ord p (P m,2 ) ≤ 4. Consequently, P m,2 is never a fifth or higher power. This extends work of Cilleruelo [6] who studied the case n = 1.
Introduction and main resultFor a prime p and a nonzero integer s, define ord p (s) to be the unique non-negative integer i for whichbe a polynomial of degree k ≥ 2 with positive leading coefficient which does not vanish at any positive integer. Setand note that this is nonzero for all m ∈ N by the above assumption.A major unsolved problem in analytic number theory concerns the question whether f represents infinitely many primes if f is irreducible and there exists no prime p dividing f (m) for all integers m. If f represents infinitely many primes, then trivially, for infinitely many integers m, there exists a prime such that ord p (A f (m)) = 1. For particular polynomials f , several authors investigated the related question whether for all sufficiently large integers m there exists a prime p with ord p (A f (m)) = 1. If this is the case, then, in particular, A f (m) is a perfect power for at most finitely many m ∈ N.Below we summarize a number of results from the literature. For the polynomial f (x) = x 2 + 1, J. Cilleruelo [6] proved the following result which we shall generalize in this paper. Theorem 1 (Cilleruelo). Let f (x) = x 2 + 1 and m > 3. Then there exists a prime divisor p of A f (m) with ord p (A f (m)) = 1. Consequently, A f (m) is a perfect power only for m = 3, in which case we have A f (3) = 10 2 . Cilleruelo's work [6] used only elementary tools such as Chebyshev's upper bound inequality for the primes counting function. In subsequent work by Fang [8], his