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Conjecture: No positive integer can be written as in more than one way

Posted on 7/7/2019
UQ ID:331
Science
Mathematics
Original

Today, I came up with the following problem when trying to solve this.

Are there distinct integers such that the equation holds? That is, is there ever an integer that can be written as in more than one way?

I claim that the answer is No, but I think solving this is beyond my knowledge. For a very preliminary observation, the simplest case is to consider the powers of , since they end in those same digits. For example, However, this brings about an issue, since there is hardly any indication as to what values and can take other than them having opposite parity.

PARI/GP code is intfun(a,b,m,n)={for(i=2,a,for(j=2,b,for(k=2,m,for(l=2,n,if(i<>k && i<>l && j<>k && j<>l && i^j+j^i-k^l-l^k==0,print(i," ",j," ",k," ",l))))));}

No solutions have been found up to .

Keywords & Tags
number-theory
modular-arithmetic
diophantine-equations
conjectures
Model Answers (9)
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K2-Think

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MBZUAI-IFM
Qwen2.5-32B
Sep 18, 2025, 01:50 PM

The problem asks whether there exist distinct integers (a, b, m, n > 1) such that (a^b + b^a = m^n + n^m). Through analyzing small values, examining the growth rates of the exponential and polynomial terms, and considering modular arithmetic and symmetry, we observe that:

  1. Symmetry and Uniqueness for Fixed (a): The function (f(a, b) = a^b + b^a) is symmetric in (a) and (b). For ...
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GPT-5

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OpenAI
Sep 2, 2025, 06:56 AM

Short answer: No proof is known. Your conjecture appears to be open. Below are some necessary conditions and reductions that any putative counterexample would have to satisfy, along with a few useful lemmas and constraints that explain why collisions (if any) are extremely rare.

  1. Symmetry and ordering
  • The expression is symmetric in the pair, so we may assume 2 ≤ a ≤ b and 2 ≤ m ≤ n. A collisi...
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Claude Opus 4

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Anthropic
Aug 1, 2025, 12:00 AM

This is an interesting conjecture that appears to be open. Let me analyze what we know and what makes this problem challenging.

The Conjecture

Conjecture: For distinct positive integers , the equation has no solutions.

Why This is Difficult

  1. Growth rates: The function grows extremely rapidly, making computational sear...
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o3 Pro

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OpenAI
Aug 1, 2025, 12:00 AM

Let

    S(a , b)  :=  a^b + b^a          (  1 < a , b ∈ ℤ  ).

Trivially S(a , b) = S(b , a).
Your question is whether there are two different ordered pairs of integers

    (a , b) ≠ (m , n) ,     a , b , m , n  > 1 ,  a ≠ b , m ≠ n ,

such that (1)

    S(a , b) = S(m , n).

In other words, can the same integer be written as a^...

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o3

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OpenAI
Aug 1, 2025, 12:00 AM

Nobody knows the answer at the moment.

If we set

    F(a , b) = a^b + b^a     (  2 ≤ a ≤ b  )

and we ask whether two different pairs (a , b) , (m , n) with {a , b} ≠ {m , n} can satisfy F(a , b)=F(m , n), the problem is open. Up-to-date literature on exponential Diophantine equations does not contain a proof either way and no counter–example has ever been published.

What is known so far ...

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DeepSeek R1

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DeepSeek
deepseek-ai/DeepSeek-R1
Aug 1, 2025, 12:00 AM
<think> I need to determine if there are distinct integers a, b, m, n all greater than 1 such that a^b + b^a = m^n + n^m. The conjecture is that no such integers exist, meaning no positive integer can be expressed as a^b + b^a in more than one way with a and b both greater than 1.

First, I should understand the behavior of the function f(a,b) = a^b + b^a. Since a and b are symmetric in a way, but...

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Gemini 2.5 Pro

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Google
Aug 1, 2025, 12:00 AM

Excellent question! This is a fascinating conjecture. The short answer is that this is a known open problem in number theory. Your conjecture that there are no such integers is widely believed to be true, but a proof has remained elusive.

Let's break down why this problem is so difficult and what is known about it.

Summary of the Situation

  1. Conjecture: There are no distinct sets o...
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Claude 3.7 Sonnet

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Anthropic
Aug 1, 2025, 12:00 AM

Uniqueness of a^b+b^a Representations in Number Theory

This is an interesting conjecture about whether any positive integer can be represented as in more than one way (with distinct values).

Analyzing the Problem

The question asks: Are there distinct integers such that ?

Let me approach this systematically:

Growth Rate Analysis

For integers...

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o4 mini

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OpenAI
Aug 1, 2025, 12:00 AM

No‐one has ever found a “non‐trivial’’ solution (i.e. with all four of a,b,m,n > 1 and the unordered pairs {a,b} ≠ {m,n}) to

  a^b + b^a = m^n + n^m.

In fact

  1. The only obvious “collision’’ is the symmetry (a,b) ↔ (b,a), which of course gives a^b + b^a = b^a + a^b. If you allow 1 as one of the exponents you get the trivial 1^n + n^1 = n + 1 = 1^(n+1) + (n+1)^1, ...
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