{ "id": "1906.06330", "version": "v1", "published": "2019-06-13T19:48:06.000Z", "updated": "2019-06-13T19:48:06.000Z", "title": "On the $x$--coordinates of Pell equations which are products of two Pell numbers", "authors": [ "Mahadi Ddamulira" ], "comment": "15 pages. arXiv admin note: text overlap with arXiv:1905.11322", "categories": [ "math.NT" ], "abstract": "Let $ \\{P_m\\}_{m\\ge 0} $ be the sequence of Pell numbers given by $ P_0=0, ~ P_1=1 $ and $ P_{m+2}=2P_{m+1}+P_m $ for all $ m\\ge 0 $. In this paper, for an integer $d\\geq 2$ which is square free, we show that there is at most one value of the positive integer $x$ participating in the Pell equation $x^{2}-dy^{2} =\\pm 1$ which is a product of two Pell numbers.", "revisions": [ { "version": "v1", "updated": "2019-06-13T19:48:06.000Z" } ], "analyses": { "subjects": [ "11A25", "11B39", "11J86" ], "keywords": [ "pell numbers", "pell equation", "coordinates" ], "note": { "typesetting": "TeX", "pages": 15, "language": "en", "license": "arXiv", "status": "editable" } } }