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Mathematics
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HJS
  • Member for 2 years, 11 months
  • Last seen more than a month ago
  • South Korea
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Student in South Korea. Interested in number theory and geometry.

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answer
6
$a_1 = a_2 = 1$ and $a_{n+2}=7a_{n+1}-a_{n}-2$ for $n \ge 1$. Prove that $a_n$ is a perfect square for every n.
Oct 2, 2021
answer
3
An $m\times n$ table has $0$ or $1$ in each cell. ($m$, $n$ even; at least one $1$.) Show that there exists a "cross" of cells whose sum is odd.
Oct 1, 2021
question
2
Solve the functional equation $f(y)f(xf(y))=f(x+y)$
Sep 29, 2021
answer
2
If $a,b,c \in \mathbb{Z}$ with $gcd(a,b)=1$ where $ab=c^n$, then $\exists d,e\in \mathbb{N}$, such that $a=d^n$ and $b=e^n$
Sep 28, 2021
answer
2
Demonstrate that $\angle AKB+\angle AFB+\angle ACB=\frac{\pi }{2}$
Sep 30, 2021
answer
2
Does the (Stirling number of the second kind) equality ${2n\brace 2} = 2^{2n-1}-1$ hold?
Oct 1, 2021
answer
1
When do two triangles reflected over midpoints have the same area?
Sep 28, 2021
answer
1
How to check if it is possible to reach every element in an array via jumps of length m (modulo N)?
Sep 29, 2021
answer
0
Let $a,b,c \in\mathbb{Z}$. Prove that if $\gcd (a,b)=1$, then $\gcd (ac,b)= \gcd(b,c)$.
Sep 28, 2021