On Prime Factors of Integers of the Form ab +

On the number of prime factors of integers of the form ab + 1

Elementary Results on the Binary Quadratic

This paper examines with elementary proofs some interesting properties of numbers in the binary quadratic form a + ab+ b, where a and b are non-negative integers. Key findings of this paper are (i) a prime number p can be represented as a + ab + b if and only if p is of the form 6k + 1, with the only exception of 3, (ii) any positive integer can be represented as a +ab+ b if and only if its all...

The power digraphs of safe primes

A power digraph, denoted by $G(n,k)$, is a directed graph with $Z_{n}={0,1,..., n-1}$ as the set of vertices and $L={(x,y):x^{k}equiv y~(bmod , n)}$ as the edge set, where $n$ and $k$ are any positive integers. In this paper, the structure of $G(2q+1,k)$, where $q$ is a Sophie Germain prime is investigated. The primality tests for the integers of the form $n=2q+1$ are established in terms of th...

Upper bounds on the solutions to n = p+m^2

ardy and Littlewood conjectured that every large integer $n$ that is not a square is the sum of a prime and a square. They believed that the number $mathcal{R}(n)$ of such representations for $n = p+m^2$ is asymptotically given by begin{equation*} mathcal{R}(n) sim frac{sqrt{n}}{log n}prod_{p=3}^{infty}left(1-frac{1}{p-1}left(frac{n}{p}right)right), end{equation*} where $p$ is a prime, $m$ is a...

ON THE GREATEST PRIME FACTOR OF (ab+ 1)(ac+ 1)

We prove that for integers a > b > c > 0, the greatest prime factor of (ab+1)(ac+1) tends to infinity with a. In particular, this settles a conjecture raised by Györy, Sarkozy and Stewart, predicting the same conclusion for the product (ab + 1)(ac + 1)(bc + 1). In the paper [GSS], Gÿory, Sarkozy and Stewart conjectured that, for positive integers a > b > c, the greatest prime factor of the prod...