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Prime numbers, diophantine equations, diophantine approximations, analytic or algebraic number theory, arithmetic geometry, Galois theory, transcendental number theory, continued fractions
1
vote
The least number of quadratic polynomials needed to cover $[1,N]$
This Not an answer but an observation about the question.
Counting the number of such polynomials which is $O(N^{1/2})$ gives a proof of Sierpinski's prime sequence theorem http://mathworld.wolfram.co …
0
votes
Definition of elementary number theory
In a book i saw a nice answer:
''Elementary Number Theory'' is Number Theory which is based on mathematics you can find in Euclid's ''Elements''
12
votes
$1$ as difference of composites with same number of prime factors
Erdos mentions in his book "Topics in the Theory of Numbers" the following:
"It is stil unkown if the equation $\omega(n+1)=\omega(n)$ has
infinitely many solutions...It is known that $|\omega …
12
votes
Accepted
Lower density of numbers not summable by consecutive integers
It is known that the only numbers not "consecutive summable" are the powers of $2$.
This is easy to prove: If $m+m+1+\ldots m+k=2^a$ then $2^a=\frac{(k+1)(2m+k)}{2}$.
This means that $2^{a+1}=(k+1)(2m …
4
votes
Harmonic sums and elementary number theory
You can find an infinite number of good numbers $n$. You can use the formula $$\frac{1}{\frac{2!}{1}}+\frac{1}{\frac{3!}{2}}+\frac{1}{\frac{4!}{3}}+...+\frac{1}{\frac{m!}{m-1}}+\frac{1}{m!}=1$$ and de …
0
votes
6
answers
595
views
If $n=x^k+y^k$ then also $n=a^2+b^2=c^3+d^3=\ldots =x^k+y^k$ [closed]
Are there infinitely many positive integers with the property:
If $n$ is a sum of two $k$th powers then it is also the sum of two $k-1$th powers, the sum of two $k-2$th powers, ... , the sum of two sq …
1
vote
3
answers
4k
views
Number of subsets with fixed cardinality k, and sum of elements a multiple of m
I need some help on a problem on combinatorics.
Let $n$ be a natural number greater than $1$ and $k,m$ be two fixed natural numbers not exceeding $n$ with $m\leq\frac{k(k+1)}{2}$.
Let $N=\{{1,2,..., …
1
vote
Looking for a reference to a classical formula for the sum of the base-$b$ digits of an integer
According to Dickson's History of the Theory of Numbers Vol. 1 page 263 at line 5:
"A. M. Legendre proved that if $p^μ$ is the highest power of the prime $p$ which divides $x!$ $\cdots$ then $$μ=\lfl …
9
votes
2
answers
276
views
For which values of $k$ is it known that there are infinitely many $n$, such that $2^{n+k}\e...
I know that there are no solutions to $2^n\equiv 1\pmod{n}$ for $n>1$ and I can prove that there are infinitely many $n$ such that $2^{n+1}\equiv1\pmod{n}$.
My question is:
Do we know other fixe …
2
votes
1
answer
80
views
Chain of sequences, such that $a_{k+1}(n)$ completes $a_k(n)$
We say that the sequence $a_{k+1}(n)$ is a complete sequence of $a_k(n)$ if:
(1) Every term of $a_k(n)$ can be written as a sum of distinct terms of $a_{k+1}(n)$.
(2) $\lim_{n\to\infty} \frac{a_k(n)}{ …
8
votes
Density of all n such that 2^n-1 is square free
To my best knowledge, we don't know even if the set $S$ has an infinity of elements.
In other words we don't know if there exist infinitely many squarefree numbers of the form $2^n-1$.
So,i think thi …
1
vote
2
answers
701
views
Numbers greater than Skewes's whose existence can be found in number theoretic proofs
Skewes has proved (without assuming RH) that $\pi(x)<Li(x)$ is violated below $e^{e^{e^{e^{7.705}}}}$ which is clearly a very large number.I was wondering if somewhere else some greater number than Sk …
3
votes
1
answer
240
views
Is $2^n -1$ finitely many times the product of consecutive primes? [duplicate]
This question was asked at MSE but recieved no attention at all.
Here it is:
Are there finitely many $(n,k) \in \mathbb{N}^2$ with $2^n-1=p_1p_2\cdots p_k$ ?
$p_1=3,p_2=5 , ...,p_k$ are consecu …
1
vote
1
answer
308
views
Radical of the sum $=$ radical of the product
My question is:
Has it been proved/disproved or studied the following?
For every $k\geq 4$ there are $k$ pairwise relatively prime numbers $a_1,a_2,...,a_k$ all greater than $1$ such that $$\t …
11
votes
3
answers
868
views
How many solutions does $\frac{1}{x_1}+\frac{1}{x_2}+\cdots +\frac{1}{x_n}=1$ have?
It is well known that $\frac{1}{2}+\frac{1}{3}+\frac{1}{6}=1$ and this is the only solution to $\frac{1}{x_1}+\frac{1}{x_2}+\frac{1}{x_3}=1$
with $2\leq x_1<x_2<x_3$.
My question is:
Let $n\in …