{ "id": "1001.4133", "version": "v4", "published": "2010-01-23T07:00:54.000Z", "updated": "2011-02-02T05:26:29.000Z", "title": "Lower bounds on the lengths of double-base representations", "authors": [ "Vassil S. Dimitrov", "Everett W. Howe" ], "comment": "8 pages, LaTeX. Added DOIs for most references; corrected a minor error in arithmetic; made small copy-editing changes. To appear in Proc. Amer. Math. Soc", "journal": "Proc. Amer. Math. Soc. 139 (2011), 3423-3430", "doi": "10.1090/S0002-9939-2011-10764-0", "categories": [ "math.NT" ], "abstract": "A double-base representation of an integer n is an expression n = n_1 + ... + n_r, where the n_i are (positive or negative) integers that are divisible by no primes other than 2 or 3; the length of the representation is the number r of terms. It is known that there is a constant a > 0 such that every integer n has a double-base representation of length at most a log n / log log n. We show that there is a constant c > 0 such that there are infinitely many integers n whose shortest double-base representations have length greater than c log n / (log log n log log log n). Our methods allow us to find the smallest positive integers with no double-base representations of several lengths. In particular, we show that 103 is the smallest positive integer with no double-base representation of length 2, that 4985 is the smallest positive integer with no double-base representation of length 3, that 641687 is the smallest positive integer with no double-base representation of length 4, and that 326552783 is the smallest positive integer with no double-base representation of length 5.", "revisions": [ { "version": "v4", "updated": "2011-02-02T05:26:29.000Z" } ], "analyses": { "subjects": [ "11A67", "11A63" ], "keywords": [ "smallest positive integer", "lower bounds", "log log log", "shortest double-base representations", "length greater" ], "tags": [ "journal article" ], "publication": { "publisher": "AMS", "journal": "Proc. Amer. Math. Soc." }, "note": { "typesetting": "LaTeX", "pages": 8, "language": "en", "license": "arXiv", "status": "editable" } } }