MathDB
Turkey NMO 2007 1st Round - P06 (Number Theory)

Source:

October 4, 2012
number theoryrelatively prime

Problem Statement

How many positive integers nn are there such that n!(2n+1)n!(2n+1) and 221221 are relatively prime?
<spanclass=′latex−bold′>(A)</span> 10<spanclass=′latex−bold′>(B)</span> 11<spanclass=′latex−bold′>(C)</span> 12<spanclass=′latex−bold′>(D)</span> 13<spanclass=′latex−bold′>(E)</span> None of the above <span class='latex-bold'>(A)</span>\ 10 \qquad<span class='latex-bold'>(B)</span>\ 11 \qquad<span class='latex-bold'>(C)</span>\ 12 \qquad<span class='latex-bold'>(D)</span>\ 13 \qquad<span class='latex-bold'>(E)</span>\ \text{None of the above}
Back to ProblemsView on AoPS