MathDB

6

Part of 2007 National Olympiad First Round

Problems(1)

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

Source:

10/4/2012
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}
number theoryrelatively prime