Bounds on the number of squares in recurrence sequences: arbitrary $b$, III

Abstract

We generalise our earlier work on the number of squares in binary recurrence sequences, $\left\{ y_{k} \right\}_{k \geq -\infty}$. In the notation of our previous papers, here we consider the case when $N_{\alpha}$ is any negative integer and $y_{0}=b^{2}$ for any positive integer, $b$. We show that there are at most $4$ distinct squares with $y_{k}$ sufficiently large. This allows us to also show that there are at most $9$ distinct squares in such sequences when $b=1,2$ or $3$, or once $d$ is sufficiently large.