IMO Shortlist 1989 problem 27
Dodao/la:
arhiva2. travnja 2012. Let

be a positive odd integer,

Find the smallest positive integer

such that

divides
%V0
Let $m$ be a positive odd integer, $m > 2.$ Find the smallest positive integer $n$ such that $2^{1989}$ divides $m^n - 1.$
Izvor: Međunarodna matematička olimpijada, shortlist 1989