Questions on more advanced topics of number theory. Consider first if (elementary-number-theory) might be a more appropriate tag before adding this tag.

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How I can calculate the algebraic rank of $C(ℚ)$

Let us consider the elliptic curve $C$ over $ℚ$ in Weierstrass form $$C:y²=x³+1$$ How I can calculate the algebraic rank of $C(ℚ)$.
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Questions on Heath-Brown's paper “Kummer’s Conjecture for Cubic Gauss Sums”

On page 21 in Heath-Brown's paper "Kummer’s Conjecture for Cubic Gauss Sums" (http://eprints.maths.ox.ac.uk/158/1/kummer.pdf), a formula says $$\sum_{j\in \mathbb{Z}[\omega]}f(j)=\sum_{k\in ...
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2answers
158 views

Largest prime number with all digits different

What is the largest prime with distinct digits? (It is certainly less than ten digits long.Can you explain it why?
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0answers
10 views

Prerequisites: Dirichlet Lectures Number Theory

I am interested in getting Dirichlet's Lectures in Number Theory but I'm afraid I don't know that much advanced math. Do I need to know things like Determinants for this book? Any list of ...
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0answers
7 views

A Extended Euclidean Algorithm related problem

I want to solved the problem in the link : http://uva.onlinejudge.org/external/100/10090.html Someone Solved this in the following way. but I can't understand how he fixed up the value of t. My ...
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0answers
24 views

Does there exist a positive integer which is a power of two, such that by rearranging it's digits we can get another power of two?

Does there exist a positive integer which is a power of two, such that by rearranging it's digits we can get another power of two? I know a quite good solution, that involves working with sum of ...
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2answers
39 views

if n is composite n divides (n-1)!

We need to prove that if n is a composite number >4, then n|(n-1)!. I wanted to ask if my observation is correct or not..what i think is that the statement can be reduced to n|(n-2)! Because n and n-1 ...
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2answers
49 views

Number analysis

I was preparing for SAT, and saw this question (without answers) and was stumped. If $2015 = 101a + 10b$, what is $a + b$? I broke $2015$ into primes, one of which is $5$, and if you break $10$ into ...
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1answer
54 views

Why do the averages of $\sin (p+\cos p )$ approach a positive limit?

$$S_1 = \sum_{k=1}^n (\sin \left[~ p(k) + \cos p(k)~ \right])$$ I wonder why this appears to give $$\frac{1}{n}S_2\sim 1/2 $$ Thanks for any insights or references. Edited in light of ...
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1answer
48 views

Proving that the multiplicative group mod p (p is prime) is cyclic

Let $\mathbb{Z}_p^*$ be the group of integers $\{1,2,3,\dots,p-1\}$ under multiplication mod $p$, where $p$ is a prime. Given the following two facts: If $d$ divides $p-1$, then there are exactly ...
4
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0answers
62 views

Representing of natural number

Let $n$ be a given natural number with $n>1$, please prove that each natural $x>=2n$ can be represented as $$x=a_1^n+a_2^n+\cdots+a_n^n-(b_1^n+\cdots+b_{n-1}^n)$$ where ...
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41 views

If $a-b,a+b,b+c,b-c,a-c,a+c$ are square number,Find minimum of the $a+b+c$

let $a,b,c$ be postive integer numbers, such $a>b>c$, and $$a-b,a+b,b+c,b-c,a+c,a-c$$ be square number. Find the $$(a+b+c)_{min}$$ My idea: let $$a-b=p^2,a+b=q^2\Longrightarrow ...
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1answer
148 views

$2 \times 3 = 5+1$ and $2+3 = 5 \times 1$. When else can we switch the operators like this?

I noticed the following: $$2 \times 3 = 5+1$$ If you switch the operators, it is still true: $$2+3 = 5 \times 1$$ There is another obvious/trivial example where you can swap the operators: $$2\times 2 ...
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1answer
46 views

Prime Factorization and Number Theory

Prime factorization of $n$ is $$n = p_1^{a_1}p_2^{a_2}p_3^{a_3}\cdots p_k^{a_k}$$ Let $f(n) = p_1^{e_1}p_2^{e_2}p_3^{e_3}\cdots p_k^{e_k}$ where $e_k=a_k$ if $p_k|a_k$, else $e_k=a_k-1$ I want to ...
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5answers
47 views

Prove that $gcd(a, b) = gcd(b, a-b)$

I can understand the concept that $\gcd(a, b) = \gcd(b, r)$, where $a = bq + r$, which is grounded from the fact that $\gcd(a, b) = \gcd(b, a-b)$, but I have no intuition for the latter.
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0answers
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a question on upper bound for Bessel function $K_{2it}(x)$

Can we have $$K_{2it}(x)\sinh(t)\ll_{x} 1$$ for $1<x< (1+|t|)^3,$ where $K_{2it}(x)$ deotes the ordinary K-bessel function and $t>1$. This is true when $x\ge (1+|t|)^3$ from some references. ...
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2answers
26 views

For part (ii), how can I prove that using Fermat's Theorem?

In this question, I think I know how to do part (i), $p^q+p^q-p-q=p(p^{q-1}-1)+q(q^{p-1}-1) $and then using Fermat's Theorem. In part (ii), I try to do $p^{q^3+q}= p^{q(q^2+1)}$, but I do not know ...
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1answer
74 views

Consequences of the negation of the Riemann hypothesis

There are many sources documenting the consequences of the Riemann hypothesis, but I can't find one discussing the consequences of its negation, particularly concerning the prime distribution.
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1answer
17 views

Concrete and elementary applications of modular forms to elliptic curves

What are some useful facts/algorithms for elliptic curves that can be obtained (proved completely) using the theory of modular forms without heavy machinery? It's often been asked what elementary ...
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0answers
25 views

about numer thorey [on hold]

For each positive integer m define Zm = {0, 1, 2, . . . , m − 1}, the set of all residues modulo m, and define C(m) = { k ∈ Zm | 0 not equal to k ≡ a^3 (mod m) for some a ∈ Z } the set of mod m ...
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0answers
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Syndeticity and A.P.-richness of certain sets

Let $A \subset \mathbb{N}: \sum_{a \in A} (\frac{1}{a}) = \infty$; denote $\{ \alpha_1 @ \alpha_2: \alpha_1, \alpha_2 \in A \} = A @ A$, where "$@$" is any appropriate binary operator. (Note: $A$ is ...
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0answers
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one-to-one correspondence with a set of primitive dirichlet charchter

Let $$\operatorname{Prim}_{N}=\{\xi \mid \xi \text{ a primitive Dirichlet charchter mod } F \text{ with } F\mid N\}$$ and $$\operatorname{Char}_{N}=\{\xi" \mid \xi" \text{ Dirichlet charchter mod } N ...
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2answers
15 views

quadratic diophantine expression

Can someone suggest a reference? Also, why are there 7 answers to the question 39*c^2 + 3*c + 1 mod 49 is congruent to 0 see my Maple worksheet. I sort of answered my own question. If 49 ...
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1answer
39 views

how to predict the sum of digits of the number $A(n)$ for a large natural $n$ without calculation, when $A(n)=a(n^2+n)+b$?

look $A(n)=9n^2+9n-1$ , let $n=15233$ , $A(15233)=2088535697$ the sum of digits of this obtained number is :$53$ and always take this form :$9k+8$ , where $k=5$ and always exist a natural number $k$ ...
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2answers
17 views

Solve for x when x is on both sides of modular equation

This question is purely out of curiosity. My little brother got a question for homework to find a rectangle where the Area = Outline. Both sides must also be integers, obviously. He found the square ...
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0answers
21 views

Previous step of the supplement to the law of cubic reciprocity

Let $\gamma$, $\rho\in\mathbb{Z[\omega]}$ be different primary irreducibles (i.e. $\gamma$, $ \rho\equiv 2(3)$), where $\omega=-\frac{1}{2}+i\frac{\sqrt{3}}{2}$. I have to prove that ...
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0answers
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Solution of Pell equation over field of p-adic numbers

Right now I am studying Pell equation. Using continued fractions, we can find the solution of Pell equation. Now my question, is it possible for me to find a solution in the field of p-adic numbers ...
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0answers
20 views

Which theorem could be used?

I want to write the $p-$adic expansion of $6!$ in $\mathbb{Q}_3$. I have to solve the congruence $x \equiv 6! \pmod {3^n}$, right? I found the following: $$x_0 \equiv 6! \pmod 3 \Rightarrow x_0 ...
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1answer
43 views

Showing two elements are coprime in a ring of integers

Let $\alpha$ and $\beta$ be the two roots of the polynomial $x^2 - x + 2$. I was wondering if someone could explain to me why $(y - \alpha)$ and $(y - \beta)$ are coprime (for any integer $y$) in the ...
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1answer
32 views

Prove the Inequality on Prime Counting Function

Is there any way to prove that, $$\pi(x^2)-\pi(y^2) \geq \sqrt{\pi(x-y)}$$ I have tried to prove it using inequalities on $\pi(x)$ but it didn't work. Can anyone help me?
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4answers
45 views

Prove that $x^2 + y^2 = 3(z^2 + m^2)$ has no solutions in integer [on hold]

Prove that: $$ x^2 + y^2 = 3(z^2 + m^2) $$ has no solutions in integer Except $0 0 0 0$
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1answer
72 views

Integral solutions of $x^5-27y^3=2x$

Find all integers $x$ and $y$ such that $x^5-27y^3=2x$.
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1answer
42 views

Given $0 < p < n$, prove there exists $n$ consecutive natural numbers such that each natural is divisible by at least $p$ distinct primes.

Given $0 < p < n$, prove there exists $n$ consecutive natural numbers such that each natural is divisible by at least $p$ distinct primes. Is there a general proof method to prove this ...
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2answers
88 views

Two math professors problem

My friend asks me a question from internet. The question is as follows Two math professors, professor Uno and professor Dos, play chess at the park while reminiscing about their past. Prof. ...
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2answers
45 views

Find all natural numbers n for which $3^n + 5^n$ is divisible by $3^{n-1} + 5^{n-1}$

Find all natural numbers n for which $3^n + 5^n$ is divisible by $3^{n-1} + 5^{n-1}$. Interested if there is a nice quick way other than mine.
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6answers
55 views

How to know a number is divisible by a given number without using a calculator?

My question is simple and comes from my curiousity during studying math. How to know a number is divisible by $7$ or $13$ without using a calculator? For example, how do we decide intuitively that ...
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0answers
30 views

What does “combining the solutions in O(n) time” mean?

Algorithm $X$ proceeds by recursively solving $5$ subproblems of one-half the size, then combining the solutions in $O(n\log n)$ time. Algorithm $Y$ makes $9$ recursively calls on ...
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1answer
33 views

How to quickly determine running time of such recurrence relations?

$$T(n)=5T(\frac{n}{2})+n\log n$$ $$T(n)=9T(\frac{n}{3})+n^2$$ $$T(n)=2T(\frac{2n}{3})+n^{1.5}$$ What are the running times of each $T(n)$? Each one looks like the form of the Master Theorem, but only ...
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2answers
27 views

Solve the recurrence $T(n)=3T(n/3)+\log n$, $T(1)=1$

So $T(n)=3T(n/3)+\log n$ and $T(1)=1$. I tried to solve this by expanding it out to see a pattern, but I don't really see the pattern: $T(n/3) = 3T(n/9)+\log (n/3)$ $T(n) = 3[3T(n/9)+\log ...
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3answers
62 views

Finding all the values of n, such that $ \varphi (n) = 12 $ [duplicate]

I have not broken this down very far. I have come to the conclusion that there are infinitely many values for n where there exists 12 coprimes to n. Since there are infinitely many primes, and primes ...
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2answers
15 views

A problem regarding Extended Euclidean Algorithm

A Linear Diophantine Equation is of the following form: Ax+By+C=0, where,gcd(A,B)=d and A=da,B=db.If (x1,y1) is a solution of the diophantine equation, every solution is of the form: x=x1+bt,y=y1−at ...
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0answers
50 views

What is known about$\sum\limits_{p\text{ prime}} \frac{1}{p^2-1}$?

Are there some known results for $\sum\limits_{p\text{ prime}} \dfrac{1}{p^2-1}$? I wasn't able to find anything about this sum in the internet or in my books!
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1answer
8 views

Solving a Extended Euclidean Algorithm related problem

Alex has some (say, n) marbles (small glass balls) and he has going to buy some boxes to store them. The boxes are of two types: Type 1: each box costs c1 Taka and can hold exactly n1 marbles Type ...
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2answers
23 views

Whether an equation has a solution

Will the following equation have a solution in $\mathbb Z$? $n_1^2+n_2^2+n_1n_2=3$ for $n_1\neq n_2$
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2answers
57 views

Determinant value of $2 \times 2$ matrices

Let $a,b,c,d$ be integers such that $\dfrac ac \in \mathbb Q^+$\ $\mathbb Z^+ $ and $\dfrac bd \in \mathbb Q^- $ \ $ \mathbb Z^-$ ; then how many solutions does $|ad-bc|=1$ have ?
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How can we solve the module function related equation?

Suppose that $\alpha,\beta=1,2,\cdots,n_1n_2$, and they satisfy the equation $$ \beta-\textbf{mod}(\beta,n_2)=\alpha-\textbf{mod}(\alpha,n_2) $$ where $\textbf{mod(,)}$ is the module function as usual ...
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2answers
64 views

Can Legendre's theorem really help solve this equation: $ax^2+by^2=cz^2$?

let $a,b,c,x,y$ be non-zero positive integers such that $$\gcd(x,y,z)=1$$ find all the non-trivial integral solutions of the diophantine equation:$$ax^2+by^2=cz^2$$ I know that the Legendre's theorem ...
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2answers
29 views

For any integer a, if $6|(3−a)$, then $3| (a−2)$.

Prove: For any integer a, if $6|(3−a)$, then $3| (a−2)$. I've been trying to work this problem for a while, but missed a day of class and can't seem to work it out.
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0answers
26 views

How many zeros within a number

Let noughts(n) be the number of noughts needed to write n in base 10.If n is given how can I find out the value of noughts(n) . I myself have tried to compute noughts(n) by examining all the digits ...
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2answers
229 views

Proving a palindromic integer with an even number of digits is divisible by 11

I'm in an introductory course for discrete math so I'm a novice at English proofs. I'm not sure if my reasoning here is valid or if I'm using modular arithmetic correctly. Specifically the line I ...