A lower bound of Ruzsa's number related to the Erdős-Turán conjecture

Csaba Sándor, Quan-Hui Yang

For a set $A\subseteq \mathbb{N}$ and $n\in \mathbb{N}$, let $R_A(n)$ denote the number of ordered pairs $(a,a^{\prime })\in A\times A$ such that $a+a^{\prime }=n$. The celebrated Erdős-Turán conjec…