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JOURNALS // Trudy Matematicheskogo Instituta imeni V.A. Steklova // Archive

Trudy Mat. Inst. Steklova, 2012 Volume 276, Pages 46–56 (Mi tm3364)

This article is cited in 4 papers

Fundamental solutions to Pell equation with prescribed size

Étienne Fouvry, Florent Jouve

Université Paris-Sud, Laboratoire de Mathématique, UMR 8628, CNRS, Orsay, France

Abstract: We prove that the number of parameters $D$ up to a fixed $x\geq2$ such that the fundamental solution $\varepsilon_D$ to the Pell equation $T^2-DU^2=1$ lies between $D^{\frac12+\alpha_1}$ and $D^{\frac12+\alpha_2}$ is greater than $\sqrt x\log^2x$ up to a constant as long as $\alpha_1<\alpha_2$ and $\alpha_1<3/2$. The starting point of the proof is a reduction step already used by the authors in earlier works. This approach is amenable to analytic methods. Along the same lines, and inspired by the work of Dirichlet, we show that the set of parameters $D\leq x$ for which $\log\varepsilon_D$ is larger than $D^\frac14$ has a cardinality essentially larger than $x^\frac14\log^2x$.

UDC: 511.68

Received in July 2011

Language: English


 English version:
Proceedings of the Steklov Institute of Mathematics, 2012, 276, 40–50

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