IMO Shortlist 1998 problem N5
Dodao/la:
arhiva2. travnja 2012. Determine all positive integers

for which there exists an integer

such that

is a divisor of

.
%V0
Determine all positive integers $n$ for which there exists an integer $m$ such that ${2^{n}-1}$ is a divisor of ${m^{2}+9}$.
Izvor: Međunarodna matematička olimpijada, shortlist 1998