Difference between revisions of "2012 IMO Problems/Problem 6"

(Created page with "Find all positive integers <math>n</math> for which there exist non-negative integers <math>a_1, a_2, \ldots, a_n</math> such that \[ \frac{1}{2^{a_1}} + \frac{1}{2^{a_2}} + \...")
 
Line 1: Line 1:
 
Find all positive integers <math>n</math> for which there exist non-negative integers <math>a_1, a_2, \ldots, a_n</math> such that
 
Find all positive integers <math>n</math> for which there exist non-negative integers <math>a_1, a_2, \ldots, a_n</math> such that
\[
+
<cmath>
 
\frac{1}{2^{a_1}} + \frac{1}{2^{a_2}} + \cdots + \frac{1}{2^{a_n}} =  
 
\frac{1}{2^{a_1}} + \frac{1}{2^{a_2}} + \cdots + \frac{1}{2^{a_n}} =  
 
\frac{1}{3^{a_1}} + \frac{2}{3^{a_2}} + \cdots + \frac{n}{3^{a_n}} = 1.
 
\frac{1}{3^{a_1}} + \frac{2}{3^{a_2}} + \cdots + \frac{n}{3^{a_n}} = 1.
\]
+
</cmath>
  
[i]Proposed by Dusan Djukic, Serbia[/i]
+
Proposed by Dusan Djukic, Serbia

Revision as of 11:46, 21 June 2018

Find all positive integers $n$ for which there exist non-negative integers $a_1, a_2, \ldots, a_n$ such that \[\frac{1}{2^{a_1}} + \frac{1}{2^{a_2}} + \cdots + \frac{1}{2^{a_n}} =  \frac{1}{3^{a_1}} + \frac{2}{3^{a_2}} + \cdots + \frac{n}{3^{a_n}} = 1.\]

Proposed by Dusan Djukic, Serbia