Demirci, Musa; Cangül, İsmail Naci; Soydan, Gökhan; Tzanakis, Nikos On the Diophantine equation \(x^2+5^a\cdot 11^b=y^n\). (English) Zbl 1237.11019 Funct. Approximatio, Comment. Math. 43, No. 2, 209-225 (2010). The authors find all solutions of the title equation in integers \(a\geq 0,~b\geq 0,~n\geq 3\), \(x>0\) and \(y>0\) with \(x\) and \(y\) coprime except when \(xab\) is odd. When \(n=4\), the proof is elementary, while for \(n\geq 5\) with \(n\neq 6\), the proof uses the theory of primitive divisors of Lucas–Lehmer sequences. The hardest case is \(n=3\), which is reduced to finding all \(\{5,11\}\)-integral points on a collection of \(36\) elliptic curves. Magma dealt successfully with \(35\) of them. For the last one, the original equation is converted into a Thue–Mahler equation, which in turn is solved using linear forms in \(p\)-adic logarithms to get some huge bounds on the potential solutions, followed by LLL to reduce such bounds and a sieve to deal with the small solutions. When \(xab\) is odd, the original equation implies that the \(n\)th term of a certain (parametric) binary recurrence is free of primes larger than \(11\), but unfortunately the binary recurrences involved are not Lucas–Lehmer sequences, so one cannot apply the theory of primitive divisors to deduce that \(n\) must be very small. Reviewer: Florian Luca (Morelia) Cited in 8 Documents MSC: 11D61 Exponential Diophantine equations 11Y50 Computer solution of Diophantine equations 11J86 Linear forms in logarithms; Baker’s method 11D25 Cubic and quartic Diophantine equations 11D59 Thue-Mahler equations Keywords:Lucas sequence; S-integral points on elliptic curves; Thue–Mahler equation; linear forms in logarithms; LLL algorithm Software:Magma PDF BibTeX XML Cite \textit{M. Demirci} et al., Funct. Approximatio, Comment. Math. 43, No. 2, 209--225 (2010; Zbl 1237.11019) Full Text: DOI arXiv Euclid OpenURL References: [1] S.A. Arif and F.S. Abu Muriefah, On Diophantine equation \(x^2+2^k=y^n\) , Int. J. Math. Math. Sci. 20 , No 2 (1997), 299–304. · Zbl 0881.11038 [2] S.A. Arif and F.S. Abu Muriefah, The Diophantine equation \(x^2+3^m=y^n\) , Int. J. Math. Math. Sci. 21 (1998), 619–620. · Zbl 0905.11017 [3] S.A. Arif and F.S. Abu Muriefah, The Diophantine equation \(x^2+5^2k+1=y^n\) , Indian J. Pure Appl. 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