Questions on more advanced topics of number theory, such as quadratic residues, primitive roots, prime numbers, non-linear Diophantine equations, etc. Consider first if (elementary-number-theory) might be a more appropriate tag before adding this tag.

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-4
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1answer
32 views

A number theory problem. [on hold]

If $\gcd(a,b) =1$, prove that $\gcd(a-b+bm, a-b+bn) = 1$ where $n= a + bm$.
0
votes
0answers
19 views

Why is the Bernoulli Number $B_1$ sometimes $+ \frac{1}{2} $?

By using the recursive formula, \begin{equation} \sum_{i=0}^{n} \binom{n+1}{i} B_i = n+1 \end{equation} we find $B_1$ to be $\frac{1}{2}$ and not $- \frac{1}{2}$. Why is this?
1
vote
2answers
40 views

What is the remainder when 50^51^52 divided by 11?

To find the remainder: $$50^{51^{52}} \mod 11$$ I have solved till: $$6^{51^{52}} \mod 11$$ But not able to proceed further. Help please.
4
votes
0answers
16 views

Dividing the whole into a minimal amount of parts to equally distribute it between different groups.

Suppose we have a finite amount of numbers $x_1, x_2, ..., x_n$ ($x_i\in\mathbb{N}$) and an object that should be divided into parts in such a way that it can be without further dividing distributed ...
0
votes
1answer
20 views

question about first occurring prime gaps

If a prime gap $g(p)$ is the first occurring prime gap of it's size, does this imply that it is also the largest gap below $p$? In other words, is the set of first occurring prime gaps contained ...
4
votes
1answer
30 views

Pair of Circles Intersect

If $S$ is a collection of circles s.t. for each point $c$ on the x-axis there is a circle in $S$ passing through the point $(c,0)$ and at the same time has the x-axis as a tangent to the circle at ...
0
votes
0answers
24 views

I want to prove that their is a binary representation for every base 10 number

I just want to make sure if my logic is right. let $x$ be a number that has no binary representation and let $y(n)$ be the closest binary representation we can get to $x$. $$y(n+1) = y(n) + 2^k$$ ...
0
votes
0answers
29 views

Algorithm to answer existential questions - Reduction

Lemma 1. For any $x$ in the ring $F[t,t^{-1}]$ ($F[t,t^{-1}]$: the polynomials in $t$ and $t^{-1}$ with coefficients in the field $F$), $x$ is a power of $t$ if and only if $x$ divides $1$ and ...
5
votes
0answers
67 views

Are there papers or books that explain why Bernhard Riemann believed that his hypothesis is true?

I would like to know what are the mathematical reasons for which Bernhard Riemann believed that his hypothesis is true, and I would like to know if those mathematical reasons were cited in his ...
3
votes
2answers
49 views

Permutations minus Transpositions

I want a formula that allows me to find all the permutations in $S_n$ (which is the set of all the integers from 1 to $n$) which don't contain a transposition. Attempt: Lets call $g(n)$ the ...
0
votes
1answer
62 views

algebra question.. [on hold]

If $f : \mathbb{R}\rightarrow \mathbb{R}$, and $f(x)=\frac{2}{4^{x}+2}$ Find the value of $$f\left [ \frac{1}{11} \right ]+f\left [ \frac{2}{11} \right ]+ \cdots +f\left [ \frac{10}{11} \right ]$$
2
votes
2answers
45 views

Terms of a certain recurrence

Let $a_1, a_2\dots $ be a sequence of reals such that $a_1 = a_2 = 1$, and $$a_{n + 2} = \frac{a_{n + 1}^3 + 1}{a_n}$$ for $n \ge 1$. It appears to be the case that all of these values are integers. ...
3
votes
1answer
56 views

Frobenius automorphism and non-split Cartan subgroup of $\mathrm{GL}_2(\mathbb{F}_p)$

For completeness I give some definitions. Let $p$ a prime number and consider $V$ a 2-dimensional $\mathbb{F}_p$-vector space. Consider $k$ a sub-algebra of $\mathrm{End}(V)$ that is a field of $p^2$ ...
3
votes
2answers
57 views

Indexes of prime Fibonacci numbers

I found this on Mathworld, but I can't seem to find any proof, either on StackExchange, nor any other site: Why do all Fibonacci primes, except for $F_4=3$, have prime indexes (with $F_0=0$)? My ...
1
vote
1answer
28 views

Fermat primality test and Fermat pseudoprime

What is the difference between Fermat primality test and Fermat pseudoprime?Can anyone explain me how we use them ?
0
votes
0answers
56 views

Zero-Sum Partitions of Nonzero Elements of a Ring

In this question, rings are not necessarily finite nor do they need to be unital (i.e., the multiplicative identity may not exist). Although I shall exclusively discuss finite commutative unital ...
-1
votes
1answer
21 views

Combining Moebius transformations

Moebius transformation in this case $\frac{az+b}{cz+d}$ for complex $z$. I have several transformations I want to apply to an initial $z$. For example first transform $f(a,b,z) = z + (a + bi) = ...
3
votes
0answers
26 views

FRACTRAN for natural numbers

Is there a simple analogue of FRACTRAN that maps a natural number to a natural number, instead of mapping a list of fractions to a natural number? One could use Gödel encoding to translate FRACTRAN ...
0
votes
3answers
27 views

Find the number of seven digit whole numbers in which only 2 and 3 are present as digits if no two 2's are consecutive in any number?

Find the number of seven digit whole numbers in which only $2$ and $3$ are present as digits if no two $2$'s are consecutive in any number? My Approach: We can make numbers and see like: ...
0
votes
1answer
30 views

If $500! = 2^m\cdot$N, where N is an odd positive integer, then find $m$

Problem : If $500! = 2^m\cdot$N, where N is an odd positive integer, then find $m$ My approach : Shall we need to expand $500!$ and then find prime factors and see what is the power of 2 in that ...
10
votes
1answer
120 views

why is $\zeta(1+it) \neq 0$ equivalent to the prime number theorem?

Reading through Titchmarh's book on the Riemann Zeta Function, chapter 3 discusses the Prime Number Theorem. One way to prove this result is to check the zeta function has no zeros on the line $z = 1 ...
3
votes
1answer
16 views

Non-additive asymptotic upper density: $\mathsf{d}^\star(A\cup B) \neq \mathsf{d}^\star(A)+\mathsf{d}^\star(B)$

Let $\mathsf{d}^\star$ be the asymptotic upper density on $\mathbf{N}$, that is, for each $X\subseteq \mathbf{N}$ we have $\mathsf{d}^\star(X)=\limsup_n |X\cap [1,n]|/n$. Then, is it possible to ...
0
votes
0answers
64 views

Sets with $n$ prime numbers

Let $n>2$ a natural number. We define the following sets: $$S=\{1 \leq a \leq n : (a,n)=1, a^{n-1} \not\equiv 1\pmod n\} \\ T=\{1 \leq b \leq n : (b,n)=1, b^{n-1} \equiv 1 \pmod n\}$$ ...
1
vote
1answer
30 views

A question on arithmetic progressions

Is it true that for every $n \in \mathbb N$ , $\exists N \in \mathbb N$ such that for any subset $A \subseteq \{1,2,...,N\}$ , either $A$ or $\{1,2,..,N\} \setminus A$ contains an arithmetic ...
11
votes
1answer
82 views

Number of polynomial factors of $a^n-b^n$?

This is a number theoretical problem that I discovered myself. Let $f(n)$ be the number of factors of $a^n-b^n$ with integer coefficients when its completely factored. For example: $f(1)=1$, because ...
8
votes
4answers
128 views

Show that $t^n-1 \mid t^m-1 \Leftrightarrow n\mid m$

I want to prove the following lemma: $t^n-1$ divides $t^m-1$ in $F[t, t^{-1}]$ if and only if $n$ divides $m$ in $\mathbb{Z}$. I have done the following: $\Leftarrow $ : $n\mid m \Rightarrow ...
0
votes
0answers
29 views

How can we show the assertion?

Every natural number not of the form $4^n(8m+7)$ where $m$ and $n$ are natural numbers, can be represented as sum of three squares.
1
vote
1answer
34 views

Good introductory book for Probabilistic Number Theory

I have a decent high school knowledge of Elementary Number Theory and it is also a subject I love to study. I have a good background in Real Analysis (not Complex Analysis) and Abstract Algbera. I ...
3
votes
0answers
71 views

Solutions to $\prod_{i=1}^{k}p_i=\sum_{i=1}^{k}p_i^2$ with $p_i$ distincts primes

Does $\prod_{i=1}^{k}p_i=\sum_{i=1}^{k}p_i^2$ with $p_i$ distincts primes and $k\geq2$ have a solution ? Here is what I already know : There is no solutions if $k\equiv0\bmod2$ or if ...
-3
votes
1answer
69 views

Other solutions to 1+1 = 2 [on hold]

Under the usual assumptions of maths and the definition of numbers we have 1 + 1 = 2. However if someone is imaginative enough we can find that: 1 + 1 = 1 (Boolean Algebra) 1 + 1 = 10 (Binary ...
1
vote
0answers
23 views

Calculating $n$-th $q:P(q)=p \in \Bbb P$

Let $P(x)$ denote the number of ways of writing an integer $x$ as a sum of positive integers (where permutation of the array of integers in the sum doesn't count). Ex: $P(1)=1, P(2)=2,P(4)=5$. Let ...
1
vote
1answer
31 views

Harmonic Identity Evidence

I was recently cleaning up my laptop when I stumbled upon a spreadsheet that I created a while ago at school when I still had an interest in math. Anyway, I remember reaching the following identity ...
1
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1answer
29 views

Quadratic reciprocity in the case $a=-1$

I am reading the proof the for odd prime $p$, $$ \left ( \frac{-1}{p} \right)_2 = (-1)^{\frac{p-1}{2}} = \begin{cases} 1 \hspace{2mm} \text{for} \hspace{2mm} p \equiv 1 \operatorname{mod} 4 \\ -1 ...
2
votes
0answers
29 views

Let $f(x)$ be defined over all rationals $x$ in $[0,1]$ and let $F(n) = \sum_{i=1}^n f(\frac in)$

also define $$F^*(n) = \sum_{i=1\,\,(i,n)=1}^n f(\frac in)$$ then prove that $$F^* = \mu * F$$ where $\mu$ is the Möebius function and the $*$ means the Dirichlet convolution. I tried the Bell series ...
1
vote
1answer
52 views

Block of integers: Divisibility

Let a < b be natural numbers. Prove that every block of b consecutive natural numbers contains two distinct elements whose product is divisible by ab. (I've proved this) Suppose now a < b < ...
3
votes
1answer
61 views

Find the sum of all primes smaller than a big number

I need to write a program that calculates the sum of all primes smaller than a given number $N$ ($10^{10} \leq N \leq 10^{14} $). Obviously, the program should run in a reasonable time, so $O(N)$ is ...
1
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0answers
34 views

If $p\mid 2^n\pm1$ with $p$ and $n$ relatively prime, then $p$ is a Wieferich prime iff $p^2$ also divides $2^n\pm 1$

The Wolfram Mathworld article on Wieferich primes states: $2^{p-1}-1\equiv 0 \mod p.$ If the first case of Fermat's last theorem is false for exponent $p$, then $p$ must be a Wieferich prime ...
0
votes
1answer
38 views

Chinese Remainder Theorem example

$$x = 4 \bmod 18$$ $$x = 52 \bmod 96$$ $$x = 6 \bmod 20$$ My current algorithm thinks the answer is $x \equiv 1066 \bmod 1440$ but I don't think there should be a solution to this. The algorithm: ...
0
votes
0answers
39 views

Proofs needed for observations regarding prime-partitionable numbers.

Definition of a prime-partitionable integer taken from W. Holsztynski, R. F. E. Strube, Paths and circuits in finite groups, Discr. Math. 22 (1987) 263-272, doi and apparently the same as in W. T. ...
2
votes
1answer
50 views

solutions for Diophantine equation for ${k_1} + 2{k_2} + 3{k_3} + … + n{k_n} = n$

Consider the Diophantine equation of the form ${k_1} + 2{k_2} + 3{k_3} + .... + n{k_n} = n$, where ${k_1},{k_2},...{k_n} \in Z^+$ . For a given $n$, how can I obtain the solutions of a given equation? ...
9
votes
2answers
422 views

Prime Numbers and a Two-Player Game

In this question, $\mathbb{N}_0$ is the set of all nonnegative integers. The notation $\mathbb{N}$ is reserved for the set of all positive integers. Alex and Beth are playing the following game. ...
1
vote
0answers
27 views

Properties of a Semi-modulo! operation

Let $A$ be an integer with its representation in base $p$ ($p$ may be prime number but not necessarily) described as: $$A=(a_ma_{m-1}\ldots a_1a_0)_{p}$$ We know $A\equiv (a_n\ldots a_1a_0)_{p}\pmod ...
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votes
0answers
51 views

How is named this property of zero parity? [on hold]

How is named then this property of zero parity? Numbers parity Any number, except zero, multiplied twice, is an even number. A pair has two elements. Demonstration: One multiplied ...
5
votes
2answers
246 views

Inequality involving a product over the primes

Is there someone who is able to prove the following statement? $$\prod_{m=1}^n \dfrac{p_m-1}{p_m} \leq \dfrac{1}{\ln(n)}$$ for all integers $n >1$ where $p_m$ is the $m$-th prime number.
5
votes
2answers
133 views

Is $a=\frac{1992!-1}{3449\times 8627}$ a prime number?

Is $a=\dfrac{1992!-1}{3449\times 8627}$ a prime number ? This is a natural follow-up to that recent MSE question We know that $a$ has $5702$ digits and no prime divisor $<10^6$.
-1
votes
1answer
68 views

What is the inverse function of gcd? [on hold]

Let $a,x,c \in\mathbb{Z}$. If $\gcd(a,x)=c$ where $a, c$ are constants and $x$ is a variable, then what values can $x$ take and how to find those values ?
1
vote
1answer
34 views

Is there an isomorphism $\mathbb{C}_p \cong \mathbb{C}_q$ for primes $p \neq q$?

Let $p \neq q$ be distinct primes. Is there a field isomorphism $\mathbb{C}_p \cong \mathbb{C}_q$? Is there a field isomorphism $\mathbb{C}_p \cong \mathbb{C}$? If such an isomorphism exists, given ...
1
vote
0answers
42 views

A question on the inequality $\bigl(\pi(x+y)\bigr)^2<4\pi(x)\pi(y)$

From the answer of this post it seems highly probable that the following problem can be proved, Show that for all sufficiently large $\min(x,y)$ we will have, ...
5
votes
1answer
40 views

Maximal $n$ such the the additive partition with a given product is unique.

Given $n$, there are many tuples with $a + b + c = n,0 < a < b < c$. For large $n$, different tuples may give the same products. E.g. $2+8+9=19=3+4+12,2\times8\times9=144=3\times4\times12$. ...
1
vote
1answer
42 views

Congruence using extended GCD

$$\eqalign{ x &\equiv 5 \mod 15\cr x &\equiv 8 \mod 21\cr}$$ The extended Euclidean algorithm gives $x≡50 \bmod 105$. I understand now that if we combine the two it implies ...