Elementary closed-forms for non-trivial divisors

Fuente: arXiv
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Main Authors: Prunescu, Mihai, Shunia, Joseph M.
Format: Preprint
Published: 2025
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author Prunescu, Mihai
Shunia, Joseph M.
author_facet Prunescu, Mihai
Shunia, Joseph M.
contents We present several elementary closed-forms that express a non-trivial divisor for every composite integer $n > 1$. Each closed-form consists of a fixed number of elementary arithmetic operations drawn from the set: addition, subtraction, multiplication, integer division, and exponentiation. Two families of closed-forms are developed. First, direct application of the hypercube method yields closed-forms $T_1(n)$, $T_2(n)$, $T_3(n)$, and $T_4(n)$ expressing the smallest prime divisor, largest non-trivial divisor, largest prime divisor, and greatest prime $\leq n$, respectively. The factorial-unwinding technique underlying these hypercube constructions leads to extreme symbolic complexity, motivating our main result: An alternative closed-form $T(n)$ that avoids factorial-unwinding by synthesizing the quadratic residue invariants $χ(n)$ (largest $r$ such that $r^2$ is a divisor) and $ω(n)$ (number of distinct prime divisors) with integer root extraction. Although evaluating these closed-forms requires exponential time, the number of arithmetic operations performed remains constant and independent of the input size $n$. This sharply contrasts with traditional algorithmic methods, where the number of operations required to locate a non-trivial divisor necessarily scales with $n$.
format Preprint
id arxiv_https___arxiv_org_abs_2510_26939
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Elementary closed-forms for non-trivial divisors
Prunescu, Mihai
Shunia, Joseph M.
Number Theory
11A51 (primary), 11A25 (secondary)
We present several elementary closed-forms that express a non-trivial divisor for every composite integer $n > 1$. Each closed-form consists of a fixed number of elementary arithmetic operations drawn from the set: addition, subtraction, multiplication, integer division, and exponentiation. Two families of closed-forms are developed. First, direct application of the hypercube method yields closed-forms $T_1(n)$, $T_2(n)$, $T_3(n)$, and $T_4(n)$ expressing the smallest prime divisor, largest non-trivial divisor, largest prime divisor, and greatest prime $\leq n$, respectively. The factorial-unwinding technique underlying these hypercube constructions leads to extreme symbolic complexity, motivating our main result: An alternative closed-form $T(n)$ that avoids factorial-unwinding by synthesizing the quadratic residue invariants $χ(n)$ (largest $r$ such that $r^2$ is a divisor) and $ω(n)$ (number of distinct prime divisors) with integer root extraction. Although evaluating these closed-forms requires exponential time, the number of arithmetic operations performed remains constant and independent of the input size $n$. This sharply contrasts with traditional algorithmic methods, where the number of operations required to locate a non-trivial divisor necessarily scales with $n$.
title Elementary closed-forms for non-trivial divisors
topic Number Theory
11A51 (primary), 11A25 (secondary)
url https://arxiv.org/abs/2510.26939