{ "id": "2005.05214", "version": "v1", "published": "2020-05-11T16:03:21.000Z", "updated": "2020-05-11T16:03:21.000Z", "title": "On a class of Labesgue-Ramanujan-Nagell equations", "authors": [ "Azizul Hoque" ], "comment": "12 Pages. Comments are most welcome!", "categories": [ "math.NT" ], "abstract": "We investigate the Diophantine equation $cx^2+d^{2m+1}=2y^n$ in integers $x, y\\geq 1, m\\geq 0$ and $n\\geq 3$, where $c$ and $d$ are given coprime positive integers such that $cd\\not\\equiv 3 \\pmod 4$. We first solve this equation for prime $n$, under the condition $n\\nmid h(-cd)$, where $h(-cd)$ denotes the class number of the quadratic field $\\mathbb{Q}(\\sqrt{-cd})$. We then completely solve this equation for both $c$ and $d$ primes, under the assumption $\\gcd(n, h(-cd))=1$. We also completely solve this equation for $c=1$ and $d\\equiv1 \\pmod 4$, under the condition $\\gcd(n, h(-d))=1$. For some fixed values of $c$ and $d$, we derive some results concerning the solvability of this equation.", "revisions": [ { "version": "v1", "updated": "2020-05-11T16:03:21.000Z" } ], "analyses": { "subjects": [ "11D61", "11D41", "11B39", "11Y50" ], "keywords": [ "labesgue-ramanujan-nagell equations", "diophantine equation", "class number", "coprime positive integers", "quadratic field" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable" } } }