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arXiv · 2411.11103

Sums of S-units in X-coordinates of Pell equations

Parvathi S Nair·Sudhansu Sekhar Rout
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Abstract

Let $S$ be a fixed set of primes and let $(X_{l})_{l\geq 1}$ be the $X$-coordinates of the positive integer solutions $(X, Y)$ of the Pell equation $X^2-dY^2 = 1$ corresponding to a non-square integer $d>1$. We show that there are only a finite number of non-square integers $d>1$ such that there are at least two different elements of the sequence $(X_{l})_{l\geq 1}$ that can be represented as a sum of $S$-units with a fixed number of terms. Furthermore, we solve explicitly a particular case in which two of the $X$-coordinates are product of power of two and power of three.

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Parvathi S Nair, Sudhansu Sekhar Rout. 2024-11-17. Sums of S-units in X-coordinates of Pell equations. https://arxiv.org/abs/2411.11103

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