Revisiting Generalized Bertand's Postulate and Prime Gaps

TL;DR

This paper generalizes Bertrand's postulate to intervals [n, kn], providing a universal proof for the lower bound on primes in these intervals and linking the upper bound to Firoozbakht's conjecture, along with a stronger bounded gaps result.

Contribution

It offers the first direct proof of the lower bound for all n ≥ 2 and connects the upper bound to Firoozbakht's conjecture, advancing prime gap theory.

Findings

Universal proof of the lower bound for all n ≥ 2.

Upper bound on primes in [n, kn] linked to Firoozbakht's conjecture.

Proved a stronger version of bounded prime gaps.

Abstract

It is a well-known fact that for any natural number $n$, there always exists a prime in $[n, 2n]$. Our aim in this note is to generalize this result to $[n, kn]$. A lower as well as an upper bound on the number of primes in $[n, kn]$ were conjectured by Mitra et al. [Arxiv 2009]. In 2016, Christian Axler provided a proof of the lower bound which is valid only when $n$ is greater than a very large threshold. In this paper, after almost a decade, we for the first time provide a direct proof of the lower bound that holds for all $n \geq 2$. Further, we show that the upper bound is a consequence of Firoozbakht's conjecture. Finally, we also prove a stronger version of the bounded gaps between primes.