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An Egyptian fraction is a sum of distinct unit fractions (reciprocals of positive integers). We show that every rational number has Egyptian fraction representations where the number of terms is of the same order of magnitude as the largest…

Number Theory · Mathematics 2007-05-23 Greg Martin

A unit fraction representation of a rational number $r$ is a finite sum of reciprocals of positive integers that equals $r$. Of particular interest is the case when all denominators in the representation are distinct, resulting in an…

Number Theory · Mathematics 2025-01-29 Greg Martin , Yue Shi

An Egyptian fraction is a sum of the form $1/n_1 + \cdots + 1/n_r$ where $n_1, \dots, n_k$ are distinct positive integers. We prove explicit lower bounds for the cardinality of the set $E_N$ of rational numbers that can be represented by…

Number Theory · Mathematics 2025-09-15 Sandro Bettin , Loïc Grenié , Giuseppe Molteni , Carlo Sanna

Any rational number can be written as the sum of distinct unit fractions. In this survey paper we review some of the many interesting questions concerning such 'Egyptian fraction' decompositions, and recent progress concerning them.

Number Theory · Mathematics 2022-10-11 Thomas F. Bloom , Christian Elsholtz

Resolving a conjecture of Zhi-Wei Sun, we prove that every rational number can be represented as a sum of distinct unit fractions whose denominators are practical numbers. The same method applies to allowed denominators that are closed…

Number Theory · Mathematics 2021-09-28 David Eppstein

We give a sharp upper bound for the entries of the representations of a rational number as a sum of Egyptian fractions.

Number Theory · Mathematics 2015-04-30 Florin Ambro , Mugurel Barcau

For any integer $N \geq 1$, let $\mathfrak{E}_N$ be the set of all Egyptian fractions employing denominators less than or equal to $N$. We give upper and lower bounds for the cardinality of $\mathfrak{E}_N$, proving that $$ \frac{N}{\log N}…

Number Theory · Mathematics 2019-07-18 Sandro Bettin , Loïc Grenié , Giuseppe Molteni , Carlo Sanna

Let $\mathcal A = (A_1,\ldots, A_n)$ be a sequence of nonempty finite sets of positive real numbers, and let $\mathcal{B} = (B_1,\ldots, B_n)$ be a sequence of infinite discrete sets of positive real numbers. A weighted real Egyptian number…

Number Theory · Mathematics 2020-04-17 Melvyn B. Nathanson

This paper introduces a new equation for rewriting two unit fractions to another two unit fractions. This equation is useful for optimizing the elements of an Egyptian Fraction. Parity of the elements of the Egyptian Fractions are also…

History and Overview · Mathematics 2020-03-31 Keneth Adrian Dagal

The notion of an \emph{Egyptian} integral domain $D$ (where every fraction can be written as a sum of unit fractions with denominators from $D$) is extended here to the notion that a ring $R$ is \emph{$W$-Egyptian}, with $W$ a…

Commutative Algebra · Mathematics 2023-09-20 Neil Epstein

Answering a question of Erd\H{o}s and Graham, we show that for each fixed positive rational number $x$ the number of ways to write $x$ as a sum of reciprocals of distinct positive integers each at most $n$ is $2^{(c_x + o(1))n}$ for an…

Combinatorics · Mathematics 2025-12-19 David Conlon , Jacob Fox , Xiaoyu He , Dhruv Mubayi , Huy Tuan Pham , Andrew Suk , Jacques Verstraëte

We discuss some examples that illustrate the countability of the positive rational numbers and related sets. Techniques include radix representations, Godel numbering, the fundamental theorem of arithmetic, continued fractions, Egyptian…

History and Overview · Mathematics 2007-05-23 David M. Bradley

We explore a novel link between two seemingly disparate mathematical concepts: Egyptian fractions and fractals. By examining the decomposition of rationals into sums of distinct unit fractions, a practice rooted in ancient Egyptian…

Number Theory · Mathematics 2024-12-16 Laura De Carli , Andrew Echezabal , Ismael Morell

The number of solutions of the diophantine equation $\sum_{i=1}^k \frac{1}{x_i}=1,$ in particular when the $x_i$ are distinct odd positive integers is investigated. The number of solutions $S(k)$ in this case is, for odd $k$: \[\exp \left(…

Number Theory · Mathematics 2016-06-08 Christian Elsholtz

Given a positive integer $n$ we let $A_k(n)$ be the number of positive integers $a$ such that $\frac{a}{n}=\frac{1}{m_1}+\frac{1}{m_2}+\cdots+\frac{1}{m_k}$ for some $m_1,m_2,\ldots,m_k\in {\mathbb N}$. We show that $x(\log x)^3\ll…

Number Theory · Mathematics 2019-09-20 Florian Luca , Francesco Pappalardi

We find the closest approximation to 1 from below using a sum of $n$ Egyptian fractions.

Classical Analysis and ODEs · Mathematics 2007-05-23 K. Soundararajan

We prove that any positive rational number is the sum of distinct unit fractions with denominators in $\{p-1 : p\textrm{ prime}\}$. The same conclusion holds for the set $\{p-h : p\textrm{ prime}\}$ for any $h\in\mathbb{Z}\backslash\{0\}$,…

Number Theory · Mathematics 2026-01-14 Thomas F. Bloom

This paper attempts to prove the Sylvester's conjecture using Egyptian Fractions with two key ingredients. First, creating a set of operators that completely generates all possible Egyptian fraction of 1. And second, to detect patterns in…

General Mathematics · Mathematics 2020-07-29 Keneth Adrian Dagal

Egyptian decompositions of 2/D as a sum of two unit fractions are studied by means of certain divisors of D, namely r and s. Our analysis does not concern the method to find r and s, but just why the scribes have chosen a solution instead…

History and Overview · Mathematics 2014-04-02 Lionel Bréhamet

Let $n,d$, and $k$ be positive integers where $n$ and $d$ are coprime. Our two main results are Theorem 1. There is a partition of the infinite interval $[kd,\infty)$ of positive integers into a family of finite sets $X$ for which the sum…

Number Theory · Mathematics 2024-12-04 Donald Silberger
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