Linear recurrences of order at most two in nontrivial small divisors and large divisors

Hung Viet Chu, Kevin Huu Le, Steven J. Miller +2

For each positive integer $N$, define $$S'_N \ =\ \{1 < d < \sqrt{N}: d|N\}\mbox{ and }L'_N \ =\ \{\sqrt{N} < d < N : d|N\}.$$ Recently, Chentouf characterized all positive integer…