Difference between revisions of "2019 IMO Problems/Problem 4"

(Created page with "Find all pairs <math>(k,n)</math> of positive integers such that <cmath>k!=(2^n-1)(2^n-2)(2^n-4)\dots(2^n-2^{n-1}).</cmath>")
 
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==Problem==
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Find all pairs <math>(k,n)</math> of positive integers such that  
 
Find all pairs <math>(k,n)</math> of positive integers such that  
  
 
<cmath>k!=(2^n-1)(2^n-2)(2^n-4)\dots(2^n-2^{n-1}).</cmath>
 
<cmath>k!=(2^n-1)(2^n-2)(2^n-4)\dots(2^n-2^{n-1}).</cmath>
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==Solution 1==

Revision as of 13:46, 15 December 2019

Problem

Find all pairs $(k,n)$ of positive integers such that

\[k!=(2^n-1)(2^n-2)(2^n-4)\dots(2^n-2^{n-1}).\]

Solution 1