Universal Solutions to gcd(n^(pk) - 1, n! - 1) > 1 via Wagstaff-Type Factors)
Year: 2026
Type: article
Abstract: This paper provides a formal and constructive solution to the open question #511226 posed on MathOverflow regarding the existence of universal solutions to gcd(n^(p*k) - 1, n! - 1) > 1 for every odd prime p >= 5. By defining the Wagstaff-type integer W_p = (2^p + 1)/3, we unconditionally prove that every prime factor q of W_p yields a universal solution given by n = q - 2, satisfying the inequality simultaneously for all integers k >= 1. The proof relies on an elegant combination of a Fermat-type congruence derived from the defining relation q | W_p with a direct application of Wilson's theorem. Immediate corollaries guarantee the existence of at least one solution for all odd primes p >= 5, establishing a precise arithmetic framework for generating explicit solutions, which are further illustrated with numerical examples for p = 5, 7, 11, and 29.
Author: Avagliano, Guido
Language: English
Subfield: Algebra and Number Theory
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7161486800
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