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Prime numbers, diophantine equations, diophantine approximations, analytic or algebraic number theory, arithmetic geometry, Galois theory, transcendental number theory, continued fractions

3 votes

Is it true that $\Phi_n(2)$ has a divisor of the form $kn+1$ for all $n\neq 6$?

In point of fact, it is well-known that if $p$ is a prime number and $a, n$ are integers that are not divisible by $p$, then $p \mid \Phi_{n}(a)$ implies $p\equiv 1 \pmod{n}$.
José Hdz. Stgo.'s user avatar
6 votes

Density and sums of reciprocals

The notion of natural density gives a suficient condition. Namely, one can prove that if $A \subseteq \mathbb{N}$ has positive upper natural density then $\sum_{a \in A} \frac{1}{a}$ diverges. This co …
José Hdz. Stgo.'s user avatar
21 votes

When n! = some Fibonacci number

There are only three terms of the Fibonacci sequence which are equal to a factorial: $$F_{1}= F_{2} = 0!=1! \quad \mbox{and} \quad F_{3}=2!$$ What is more, F. Luca proved in this paper (published in …
José Hdz. Stgo.'s user avatar
5 votes

Upper bound for maximal gap between consecutive numbers consisting only $4k+1$ primes

Short answer: yes. In „Zur Verallgemeinerung des Bertrandschen Postulates, daß zwischen $x$ und $2x$ stets Primzahlen liegen" (Mathematische Zeitschrift, 34 (1932), pp. 505-526), R. Breusch proved tha …
José Hdz. Stgo.'s user avatar
5 votes

FLT from Mochizuki's proof of abc

Let us suppose that $x^{n}+y^{n}= z^{n}$ with $x, y,$ and $z$ relatively prime. By the abc conjecture, $|x^{n}|\ll |xyz|^{1+\epsilon}$, $|y^{n}|\ll |xyz|^{1+\epsilon}$, and $|z^{n}|\ll |xyz|^{1+\epsil …
José Hdz. Stgo.'s user avatar
19 votes
4 answers
18k views

On the series 1/2 + 1/3 + 1/5 + 1/7 + 1/11 + ...

It is well-known that A: The series of the reciprocals of the primes diverges My question is whether property A is in some sense a truth strongly tied to the nature of the prime numbers. Property A …
José Hdz. Stgo.'s user avatar
10 votes

Integral polynomials dividing N!

Wow! I have been thinking about this problem, too. I can prove that for every odd natural number $d$ there exists infinitely many $n \in \mathbb{N}$ such that $n^{d}+1 \mid n!$. Here you have my gorge …
José Hdz. Stgo.'s user avatar
5 votes

Trost's Discriminant Trick

As I was browsing through the problems & solutions department of the American Mathematical Monthly the other day, I found out that, in his solution to problem E-2332 [1972, 87], which was published on …
José Hdz. Stgo.'s user avatar
2 votes

Bertrand's postulate

It has to be noted that we can also give a (conditional) proof of Bertrand's Postulate assuming the veracity of Goldbach's Conjecture. This was the subject matter of a filler piece that appeared on pa …
José Hdz. Stgo.'s user avatar
3 votes
2 answers
467 views

Character sums: reference request

This one will be quick... Wonder if anybody knows or remembers the title of the paper in which Karatsuba introduced his approach at Burgess's bound on character sums. Thanks for your support. EDIT. …
José Hdz. Stgo.'s user avatar
10 votes
Accepted

Is every prime greater than 5, less than the sum of the two previous primes?

I am to elaborate a bit on how it is that the answer I left in this previous question implies a positive answer to Mr. Recamán's question. By elementary means (i.e., without resorting to any complex …
José Hdz. Stgo.'s user avatar
16 votes

Diophantine equation $3^n-1=2x^2$

W. Ljunggren proved in 1 that the Diophantine equation $$\frac{x^{n}-1}{x-1} = y^{2}$$ doesn't admit solutions in integers $x>1, y>1, n>2$, except when $n=4, x=7$ and $n=5, x=3$. Since your equation …
José Hdz. Stgo.'s user avatar
8 votes
Accepted

Chebyshev's approach to the distribution of primes

Erdős and Diamond proved in [1] that Chebyshev could have achieved sharper bounds for the asymptotic behavior of the prime counting function. Nevertheless, their proof does not shed any light on the f …
José Hdz. Stgo.'s user avatar
3 votes
1 answer
855 views

A limit involving the totient function

P. Erdős and Leon Alaoglu proved in [1] that for every $\epsilon > 0$ the inequality $\phi(\sigma(n)) < \epsilon \cdot n$ holds for every $n \in \mathbb{N}$, except for a set of density $0$. C. L. me …
José Hdz. Stgo.'s user avatar
2 votes
3 answers
336 views

Gauss sums over multiplicative subgroups

Hello, Is anyone here aware of a well-motivated exposition of the Bourgain-Glibichuk-Konyagin estimate for exponential sums (or Gauss sums) over multiplicative subgroups? If any of you has a write-up …
José Hdz. Stgo.'s user avatar

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