Three expressions of the $n$-th prime number: discrete sieving, spectral analysis and probabilistic dynamics
Jean-Christophe Pain
TL;DR
This paper investigates how to express the $n$-th prime using three distinct viewpoints that balance asymptotic density with discrete structure. It develops an exact discrete sieving formula via a Möbius-derived coprimality indicator, a phenomenological spectral resonance model based on von Mangoldt weighting and a Riemann-type oscillatory term, and a survival-dynamics/information-theoretic framework anchored in Mertens' theorem and Selberg sieve concepts. The first yields an exact identity for $p_{n+1}$ with computable sub-exponential complexity; the second offers a bounded spectral reconstruction whose primes act as points of constructive interference; the third models prime emergence as capacity-driven growth constrained by entropy, including capacity depletion and twin-prime considerations. Together, these approaches form a multi-scale framework that connects analytic number theory, sieve theory, and information theory, offering a richer picture of prime distribution beyond traditional asymptotics and suggesting new directions for understanding discrete arithmetic realities.
Abstract
The search for a closed-form expression of the $n$-th prime number, $p_n$, has long oscillated between the rigid determinism of analytic functions and the apparent randomness of local distributions. This paper explores three different approaches to $p_n$. The first one formalizes an analytical identity for $p_{n}$ based on a harmonic summation filtered by a Möbius-derived coprimality indicator. Unlike Gandhi's 1971 identity, which employs a geometric density and logarithmic extraction, this formula operates through a discrete summation over the range defined by Bertrand's postulate. In the second one, we refine the ``harmonic resonance'' model, which posits that primes emerge as spectral nodes from von Mangoldt oscillations. Third, we adopt a ``survival dynamics'' approach, inspired by Mertens' theorems, treating prime spacing as an evolutionary growth process. By bridging these perspectives, we offer a comprehensive framework for understanding the transition from asymptotic trends to discrete arithmetic realities.
