Art of Problem Solving

2019 USAMO Problems/Problem 1: Difference between revisions

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==Problem 1==
==Problem==
Let <math>\mathbb{N}</math> be the set of positive integers. A function <math>f:\mathbb{N}\to\mathbb{N}</math> satisfies the equation <cmath>\underbrace{f(f(\ldots f}_{f(n)\text{ times}}(n)\ldots))=\frac{n^2}{f(f(n))}</cmath>for all positive integers <math>n</math>. Given this information, determine all possible values of <math>f(1000)</math>.
Let <math>\mathbb{N}</math> be the set of positive integers. A function <math>f:\mathbb{N}\to\mathbb{N}</math> satisfies the equation <cmath>\underbrace{f(f(\ldots f}_{f(n)\text{ times}}(n)\ldots))=\frac{n^2}{f(f(n))}</cmath>for all positive integers <math>n</math>. Given this information, determine all possible values of <math>f(1000)</math>.



Revision as of 23:06, 19 April 2019

Problem

Let $\mathbb{N}$ be the set of positive integers. A function $f:\mathbb{N}\to\mathbb{N}$ satisfies the equation \[\underbrace{f(f(\ldots f}_{f(n)\text{ times}}(n)\ldots))=\frac{n^2}{f(f(n))}\]for all positive integers $n$. Given this information, determine all possible values of $f(1000)$.

Solution

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See also

2019 USAMO (ProblemsResources)
First Problem Followed by
Problem 2
1 2 3 4 5 6
All USAMO Problems and Solutions