## IMO 2019/P4

Discussion on International Mathematical Olympiad (IMO)
tanmoy
Posts: 289
Joined: Fri Oct 18, 2013 11:56 pm

### IMO 2019/P4

Find all pairs $(k,n)$ of positive integers such that $k!=(2^n-1)(2^n-2)\cdots(2^n-2^{n-1})$

Proposed by Gabriel Chicas Reyes, El Salvador
"Questions we can't answer are far better than answers we can't question"

Abdullah Al Tanzim
Posts: 24
Joined: Tue Apr 11, 2017 12:03 am

### Re: IMO 2019/P4

Solution:
Everybody is a genius.... But if you judge a fish by its ability to climb a tree, it will spend its whole life believing that it is stupid - Albert Einstein