{ "id": "2301.06970", "version": "v1", "published": "2023-01-17T15:44:20.000Z", "updated": "2023-01-17T15:44:20.000Z", "title": "Infinitely many primes in each of the residue classes $1$ and $8$ modulo $9$ are sums of two rational cubes", "authors": [ "Somnath Jha", "Dipramit Majumdar", "B. Sury" ], "categories": [ "math.NT" ], "abstract": "Given an integer $n$, it is a classical Diophantine problem to determine whether $n$ can be written as a sum of two rational cubes. The study of this problem has a copious history that can be traced back to the works of Sylvester, Satg{\\'e}, Selmer etc. and up to the recent works of Alp{\\\"o}ge-Bhargava-Shnidman. In this short note, we prove that infinitely many primes congruent to $1$ modulo $9$ are sums of two rational cubes and that infinitely many primes congruent to $8$ modulo $9$ are sums of two rational cubes. Among other results, we prove also that every residue class $a \\pmod {q}$ (for any prime $q$ and any integer $a$ co-prime to $q$) contains infinitely many primes which are sums of two rational cubes. Further, we provide many infinite families of composite numbers which are rational cube sums.", "revisions": [ { "version": "v1", "updated": "2023-01-17T15:44:20.000Z" } ], "analyses": { "keywords": [ "residue class", "primes congruent", "rational cube sums", "classical diophantine problem", "infinite families" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }