IMO Shortlist 2002 problem N3
Dodao/la:
arhiva2. travnja 2012. Let

be distinct primes greater than

. Show that

has at least

divisors.
%V0
Let $p_1,p_2,\ldots,p_n$ be distinct primes greater than $3$. Show that $2^{p_1p_2\cdots p_n}+1$ has at least $4^n$ divisors.
Izvor: Međunarodna matematička olimpijada, shortlist 2002