Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 38851

Diophantine equations are polynomial equations $F=0$, or systems of polynomial equations $F_1=\ldots=F_k=0$, where $F,F_1,\ldots,F_k$ are polynomials in either $\mathbb{Z}[X_1,\ldots,X_n]$ of $\mathbb{Q}[X_1,\ldots,X_n]$ of which it is asked to find solutions over $\mathbb{Z}$ or $\mathbb{Q}$. Topics: Pell equations, quadratic forms, elliptic curves, abelian varieties, hyperelliptic curves, Thue equations, normic forms, K3 surfaces ...

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 …
Konstantinos Gaitanas's user avatar
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 …
Konstantinos Gaitanas's user avatar
10 votes
0 answers
221 views

Product of four consecutive primes plus $1$ equals square

Some days ago, I noticed that $3\cdot 5\cdot 7\cdot 11 +1=34^2$. I am almost sure that if we denote four consecutive primes by $p, q, r, s$ then the equation $$p\cdot q\cdot r\cdot s+1=x^2 \qua …
Konstantinos Gaitanas's user avatar
16 votes
Accepted

Is there an algorithm to solve quadratic Diophantine equations?

Sierpsinski proved that whenever this diophantine equation does not have a solution for $x$ then $x^2+(x+1)^2$ is prime. It is conjectured also by Sierpinski that there are infinitely many primes of t …
Konstantinos Gaitanas's user avatar
7 votes
2 answers
396 views

An equation involving perfect numbers

Let $s,x_1,x_2,\cdots, x_s$ be natural numbers not neccesarily distinct. I am interested in solving the equation $$(x_1+x_2+\cdots +x_s)^s=2^s(x_1\cdot x_2\cdots x_s)^2$$ Some Notes: I have found t …
Konstantinos Gaitanas's user avatar
31 votes
5 answers
8k views

Fermat's proof for $x^3-y^2=2$

Fermat proved that $x^3-y^2=2$ has only one solution $(x,y)=(3,5)$. After some search, I only found proofs using factorization over the ring $Z[\sqrt{-2}]$. My question is: Is this Fermat's original p …
Konstantinos Gaitanas's user avatar
7 votes
Accepted

A new result on the Diophantine equation $x^3 + y^3 +z^3 = 3$

My opinion is: Step 1. Repeat the arguments you use in your proofs again and again. If you are still sure that you have some new (valid) things to say about the equation then go to Step 2. Learn how t …