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Questions tagged [number-theory]

A field of mathematics studying numbers, their properties and structures that arise from them.

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9 votes
2 answers
1k views

Who was N.M. Stephens who refuted the Stronger Feit-Thompson Conjecture?

The Stronger Feit-Thompson conjecture states that: There exist no distinct prime numbers $p$ and $q$ such that: $\dfrac {p^q - 1} {p - 1}$ and $\dfrac {q^p - 1} {q - 1}$ are not coprime. This was ...
1 vote
0 answers
96 views

Why Did Riemann Venture into Number Theory for the Riemann Hypothesis?

I’m exploring the history behind the Riemann Hypothesis and I found something interesting. We know that Bernhard Riemann was mainly focused on complex analysis, but he also wrote a very important ...
16 votes
1 answer
2k views

Who was Nicolò Paganini that discovered the amicable pair 1184, 1210?

Nicolò Paganini (not the violinist) was a 16 yo Italian schoolboy when he discovered that 1184 and 1210 form a pair of amicable numbers. It is in fact, the 2nd smallest such pair, and it did escape ...
3 votes
1 answer
639 views

Where did Lagrange prove the Four Squares Theorem?

I am trying to confirm the initial publication of Lagrange's Four Squares Theorem. Most of my sources give that it was proved by him in $1770$. However, the generally very good Penguin Dictionary of ...
8 votes
3 answers
624 views

How could the people of the past be sure that $a \times b = b \times a$?

Let me quote from Terence Tao "Analysis 1": Historically, the realization that numbers could be treated axiomatically is very recent, not much more than a hundred years old. Then, how ...
1 vote
0 answers
52 views

Was Euler aware of the general form of the characterization of primes of the form $p=x^2+ny^2$ for arbitrary $n>0$?

If $n$ is a positive integer then there is a monic irreducible polynomial $f(x)$ such that if $p$ is an odd prime not dividing $n$ nor the discriminant of $f$ then $$ p=x^2+ny^2\iff \left(\frac{-n}{p}\...
3 votes
1 answer
175 views

How did Gauss determine the number of primes?

In Brian Conrey's article on Riemann's hypothesis, one reads in the very beginning: On Christmas Eve 1849 Gauss wrote a letter to his former student Encke in which he described his thoughts about the ...
1 vote
1 answer
105 views

David Hilbert's paper: Substitution of the group of cyclotomic field

A question about a notation in David Hilberts's "Ein neuer Beweis des Kroneckerschen Fundamentalsatzes über Abelsche Zahlkörper" (here a german online available source, not sure if there ...
0 votes
0 answers
92 views

History of Bernoulli numbers

I have been trying to understand what is the meaning of Bernoulli numbers, but to my mind it has been obscured behind complicated formulas without much explaination. I presume finding the history ...
0 votes
0 answers
52 views

History of prime distribution $\lim_{x\to\infty}\frac{\pi(x)}{x}=0$

Let $\pi(x)$ be the prime counting function. It is well-known that $$\lim_{x\to\infty}\frac{\pi(x)}{x}=0.$$ My question is who is the first person to prove this result? Did Eratosthenes prove this ...
2 votes
1 answer
232 views

Implications of several unpublished "binomial congruences" of Gauss

In article 23 of his first memoir on biquadratic residues, Gauss gave the first example of a binomial-type congruence, which is apparently a quite "deep" result - many authors relate it to ...
3 votes
1 answer
115 views

Finite fields as quotients

Although finite fields are usually introduced as field extensions of fields of prime order, they also arise as quotients of number rings; e.g., $GF(9)$ comes from taking the Gaussian integers mod 3 ...
4 votes
0 answers
179 views

Who proposed terminating decimals as a major set and why are them important in France?

After looking at some school sources in French, it is common to provide the various number sets in the following order $$\mathbb{N}\subset \mathbb{Z}\subset\mathbb{D}\subset\mathbb{Q}\subset\mathbb{R}\...
0 votes
1 answer
273 views

Question about Felix Klein's "Development of Mathematics in the 19th Century" [closed]

The original version of these photos is Felix Klein's "Development of Mathematics in the 19th Century" In second photo In this book, it says class-field and decompose 2 into $(1+i)$ and $(1-...
1 vote
0 answers
61 views

Unramified étale cohomology groups & unramified Milnor-Witt K-groups: any relation to notion of unramifiedness in number theory

Let $X$ be an integral locally noetherian smooth scheme over base field $k$. Then for every point $x \in X^{(1)}$ of codimension $1$, the stalk $\mathcal{O}_{X,x}$ is a discrete valuation ring. ...
4 votes
1 answer
117 views

Teiji Takagi's Fondation of Class Field Theory in Terms of Norms

I have a question about Teiji Takagi's original motivation for his groundbreaking reformulation of class field theory implementing the ideal norms $N_{\mathfrak{m}}(L/K)$ as new "key players"...
2 votes
2 answers
141 views

Background of 'Eisenstein series'

It's my first question. I am studying elliptic function, Among them, I have a question about the Weierstrass elliptic function. In the Weierstrass elliptic function, their coefficients are expressed ...
1 vote
1 answer
110 views

How did Fermat handle Frenicle's challenge to find a perfect number between $10^{20}$ and $10^{22}$?

Even perfect numbers have the form $(2^n - 1)2^{n-1}$ where $2^n - 1$ is a prime number. This restricts the possible values of $n$ to $34, 35, 36, 37$. Since $n$ must be prime, only $37$ has to be ...
3 votes
0 answers
100 views

When did modular forms start to get studied via algebraic geometry?

I'm looking, for instance, as to when people started studying modular curves and modular forms as sections of line bundles on them, as opposed to the point of view of modular forms being holomorphic ...
16 votes
2 answers
3k views

Did ancient Greek mathematicians consider numbers independently of geometry?

I am currently reading Oliver Bryne's edition of Euclid's Elements, and in The Elements many arithmetic propositions are proved geometrically, and it feels to me that numbers are always treated as ...
2 votes
1 answer
282 views

Why is the claim that $\pi$ contains all natural numbers thought by the general public to be proven, despite it being conjecture currently?

We've all heard the popular claim that the expansion of $\pi$ contains every natural number; however, as we can see from numerous sources, such as Mathematics Stack Exchange and Wikipedia, it is ...
1 vote
1 answer
92 views

When was the first time the number 0 came to mean a multiple of ten? [closed]

The earliest number notation I can find is the sexagesimal digit notation of cuneiform. From my understanding of that, in order to make numbers bigger than 60, you would just add the smaller numbers ...
2 votes
0 answers
106 views

Influence of Edmund Landau's list of four problems

At the 1912 International Congress of Mathematicians, Edmund Landau listed four basic problems about prime numbers: Goldbach's conjecture, the twin prime conjecture, Legendre's conjecture (that there ...
3 votes
0 answers
240 views

Who came up with the proof of "Bézout's identity" that uses the well-ordering principle?

Let $a$ and $b$ be two integers not both of which are equal to zero. It is an important and well-known fact that $\text{gcd}(a,b)=ax_{0}+by_{0}$ for some integers $x_{0}$ and $y_{0}$. Even though this ...
21 votes
0 answers
696 views

What is the modern significance of Theaetetus's classification of quadratic irrationals?

Before Eudoxus's theory of proportion there was a theory of irrationals based on continued fraction expansions, which Fowler calls anthyphairesis. Theaetetus is said to develop a classification of ...
1 vote
1 answer
96 views

The symbol h for class numbers

We use $h_K$ conventionally to denote the class numbers of number fields $K$. But I have never thought why the letter $h$ was used for it. Why and who used $h$ for the class number?
5 votes
1 answer
320 views

Hilbert's problem list did not include Fermat's last theorem. Why?

Fermat's Last Theorem was open for more than 350 years until Andrew Wiles proved it in 1995. Are there possible (historical or other) reasons why David Hilbert did not include this famous open problem ...
6 votes
1 answer
3k views

Who discovered this closed form formula for the n-th prime number?

The following is a formula for the $n$-th prime number ($[\,]$ represents the floor function). Who was the first person to discover it? $$\newcommand{\lowerbrack}[2]{% \raise{-#1}{\left[\raise{#1}{#...
3 votes
1 answer
277 views

When and where was Legendre's Conjecture first published?

When and where did Legendre first publish or write about his conjecture that there is a prime between consecutive square numbers? $$n^2 < p < (n+1)^2$$ I have looked through edition 1 and 2 of ...
4 votes
1 answer
245 views

Who first proved necessity of Euclid's formula for pythagorean triples?

The following well-known formula for pythagorean triples is commonly called Euclid's formula: If $a, b, c$ are three natural numbers with $a,c$ odd, $b$ even, $\gcd(a,b,c)=1$ and $a^2+b^2=c^2$, then ...
3 votes
1 answer
203 views

When was the study of automorphic (and in particular modular) forms become "adelized"?

The theory of automorphic forms is stated in modern language as a function on the adelic points of some reductive group satisfying certain properties (see for instance, Chapter 7 of An Introduction to ...
16 votes
7 answers
3k views

Have numbering systems other than base ten ever been used or popular?

Base ten makes a lot of sense as a numbering system, given the number of digits humans typically have on their hands. That said, some older money systems weren't based on the number of fingers we ...
5 votes
0 answers
467 views

Origin of Problem 6 on the 1988 International Mathematical Olympiad

The recent Numberphile video on the famous Problem 6 of the 1988 IMO (mentioned in a recent answer on this site) got me wondering: Who came up with this problem in the first place, and how did they ...
4 votes
2 answers
117 views

Special quadratic reciprocity? $(-3/p)_2$ and $(5/p)_2$ in addition to $(-1/p)_2$ and $(2/p)_2$?

Context: since $\mathbb Z/p^\times$ is cyclic for $p$ prime, $-1$ is a square mod $p$ if and only if $(-1)^{{p-1\over 2}}=1$. A significantly subtler, but still classical, case is determining the ...
3 votes
2 answers
1k views

Pythagorean and the number 17

I was looking for some properties of the prime numbers, and I found some curiosities of the number 17 in that site. One of them is this 17 was called by the Pythagoreans - opposition, obstruction,...
1 vote
1 answer
138 views

Number theory: a quote

I remember reading a remark on number theory that went something like this: "there is plenty of material in this topic for an $n$ semester course without having to repeat oneself". Have you ...
2 votes
2 answers
287 views

Simplest of the many proofs the prime harmonic series diverges

Over the history of mathematics, some key facts have had multiple and different proofs developed for them. Sometimes these different proofs provide a unique insight or understanding of those facts. ...
4 votes
0 answers
114 views

Who first proved that there is no five-digit perfect number?

A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. The first five perfect numbers are 6, 28, 496, 8128, and 33550336. Nicomachus ...
1 vote
1 answer
136 views

Fermat et l'équation de Pell

Does any of you happen to own and electronic copy of the paper "Fermat et l'équation de Pell" by A. Weil? If I understand correctly, this paper can be found on pages 413-419 of the third ...
10 votes
1 answer
12k views

How much did John Nash contribute to proving the Riemann hypothesis?

At quite the end of the movie A Beautiful Mind, John Nash tells a student "I am making progress" (towards proving the Riemann hypothesis (RH)). Actually, how much did Nash contribute to the ...
9 votes
1 answer
1k views

Why is the Sophie Germain Identity called thus?

Several authors (z.B.: Arthur Engel in his Problem-Solving Strategies, Alexander Bogomolny in this entry of the Cut the Knot website) refer to the following (straightforward) consequence of the ...
4 votes
2 answers
186 views

Original Statement and Proof of Chebyshev’s $\vartheta(x) \sim x$

I am looking for an online source that gives the original statement and proof of Chebyshev’s asymptotic relation $\vartheta(x)\sim x$ where $\vartheta(x)=\sum_{p\leq x}\log p$. I have tried ...
4 votes
1 answer
151 views

$\pi(x)$ and $\operatorname{li}(x)$ cross infinitely many times -- due to Littlewood 1914 or Schmidt 1903?

In Montgomery-Vaughan's Multiplicative Number Theory I: Classical Theory, they prove in Theorem 15.3 that $\pi(x)-\operatorname{li}(x) = \Omega_{\pm}(x^{\Theta-\epsilon})$ for every $\epsilon>0$ ...
8 votes
2 answers
250 views

How did Mersenne discover Mersenne primes?

So, I was wondering, how did Mersenne come up with the formulae $2^p-1$? Do we have any ideas of how it came to be?
4 votes
1 answer
267 views

Whose 1930 number theory result is used in characterizing perfect 2-error correcting linear codes?

In Error-Correcting Codes: A Mathematical Introduction (Chapman & Hall, 1998), John Baylis wrote (p.109) Moving on to 2-error correcting linear codes, the condition for perfection of linear codes ...
2 votes
1 answer
195 views

(Where) does Plato define perfect number?

I've read several texts suggesting that Plato defines "perfect number" in his Republic, book VIII 546 b. However, there's no definition as we can see from - for example - this translation: &...
4 votes
1 answer
183 views

Why did Gauss use [1] modulus and [2] its ablative case to define n as a positive divisor of a - b?

Any Latinists here please? 1. Why did Gauss choose modulus? How does it relate to $n >1$ where $a - b = kn$ for some integer $k$? And why the Ablative Case? ag.algebraic geometry - The Origin(s) ...
8 votes
3 answers
618 views

Who was L. Aubry?

In his magnificent book Number Theory: An approach through history, from Hammurapi to Legendre, André Weil quotes the article Solution de quelques questions d'analyse indéterminée, by L. Aubry (Sphinx-...
1 vote
0 answers
130 views

How did Fermat come up with his Last Theorem?

It's usually believed that Fermat's claim that he had a proof for the Last Theorem is false, and that it might have been more of a conjecture. Or considering it took many centuries and advanced ...
7 votes
2 answers
482 views

$2^{11} - 1$ and the mystery of Huldaricus Regius

While researching on Mersenne numbers, I often stumble upon statements of this nature (it is not verbatim): Huldaricus Regius in 1536 proved that $2^{11}-1$ is not prime, providing a factorisation ...