We provide numerical evidence towards three conjectures on harmonic numbers by Eswarathasan, Levine and Boyd. Let Jp denote the set of integers n ≤1 such that the harmonic number Hn is divisible by a prime p. The conjectures state that: (i) Jp is always finite and of the order O(p2(log log p) 2+); (ii) the set of primes for which Jp is minimal (called harmonic primes) has density e-1 among all primes; (iii) no harmonic number is divisible by p4. We prove parts (i) and (iii) for all p ≤ 16843 with at most one exception, and enumerate harmonic primes up to 50 105, finding a proportion close to the expected density. Our work extends previous computations by Boyd by a factor of approximately 30 and 50, respectively.

ON ESWARATHASAN–LEVINE AND BOYD’S CONJECTURES FOR HARMONIC NUMBERS

LEONARDO CAROFIGLIO;
2025-01-01

Abstract

We provide numerical evidence towards three conjectures on harmonic numbers by Eswarathasan, Levine and Boyd. Let Jp denote the set of integers n ≤1 such that the harmonic number Hn is divisible by a prime p. The conjectures state that: (i) Jp is always finite and of the order O(p2(log log p) 2+); (ii) the set of primes for which Jp is minimal (called harmonic primes) has density e-1 among all primes; (iii) no harmonic number is divisible by p4. We prove parts (i) and (iii) for all p ≤ 16843 with at most one exception, and enumerate harmonic primes up to 50 105, finding a proportion close to the expected density. Our work extends previous computations by Boyd by a factor of approximately 30 and 50, respectively.
2025
1
11
11B83; 11Y55; 11Y70; 2020 Mathematics subject classification
LEONARDO CAROFIGLIO; GIACOMO CHERUBINI; ALESSANDRO GAMBINI
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/2143033
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