{ "id": "1710.05960", "version": "v1", "published": "2017-10-16T18:50:48.000Z", "updated": "2017-10-16T18:50:48.000Z", "title": "Bisected theta series, least $r$-gaps in partitions, and polygonal numbers", "authors": [ "Cristina Ballantine", "Mircea Merca" ], "comment": "10 pages", "categories": [ "math.CO", "math.NT" ], "abstract": "The least $r$-gap, $g_r(\\lambda)$, of a partition $\\lambda$ is the smallest part of $\\lambda$ appearing less than $r$ times. In this article we introduce two new partition functions involving least $r$-gaps. We consider a bisection of a classical theta identity and prove new identities relating Euler's partition function $p(n)$, polygonal numbers, and the new partition functions. To prove the results we use an interplay of combinatorial and $q$-series methods. We also give a combinatorial interpretation for $$\\sum_{n=0}^\\infty (\\pm 1)^{k(k+1)/2} p(n-r\\cdot k(k+1)/2).$$", "revisions": [ { "version": "v1", "updated": "2017-10-16T18:50:48.000Z" } ], "analyses": { "subjects": [ "05A17", "11P83" ], "keywords": [ "bisected theta series", "polygonal numbers", "identities relating eulers partition function", "series methods", "combinatorial interpretation" ], "note": { "typesetting": "TeX", "pages": 10, "language": "en", "license": "arXiv", "status": "editable" } } }