Correlated sums of $r(n)$

Abstract

We prove an asymptotic formula for $\displaystyle \sum_{n\leq N}r(n)r(n+m)$ using the spectral theory of automorphic forms and we specially study the uniformity of the error term in the asymptotic approximation when $m$ varies. The best results are obtained under a natural conjecture about the size of a certain spectral mean of the Maass forms. We also employ large sieve type inequalities for Fourier coefficients of cusp forms to estimate some averages (over $m$) of the error term.