Published online by Cambridge University Press: 20 November 2018
Throughout this article c0, c1, c2, … will denote effectively computable positive absolute constants. Denote the cardinality of a set X by |X|. Let N be a positive integer and let A and B be non-empty subsets of {1, …,N}. Put
In [3], Balog and Sá;rközy proved that if N > c0 and
(1)
then there exist a0 and b0 with a0 ∊ A0 and b0 ∊ B0 and a prime number p such that
and
(2)
If follows from this result that if |A| ≫ N and |B| ≫ N then there exist a in A and b in B and a prime p such that p2|(a + b) with