MathDB
GCD of a Sequence

Source:

June 8, 2009
number theorygreatest common divisormodular arithmetic

Problem Statement

The largest of the following integers which divides each of the numbers of the sequence 1^5 \minus{} 1,\, 2^5 \minus{} 2,\, 3^5 \minus{} 3,\, \cdots, n^5 \minus{} n, \cdots is: <spanclass=latexbold>(A)</span> 1<spanclass=latexbold>(B)</span> 60<spanclass=latexbold>(C)</span> 15<spanclass=latexbold>(D)</span> 120<spanclass=latexbold>(E)</span> 30 <span class='latex-bold'>(A)</span>\ 1 \qquad <span class='latex-bold'>(B)</span>\ 60 \qquad <span class='latex-bold'>(C)</span>\ 15 \qquad <span class='latex-bold'>(D)</span>\ 120\qquad <span class='latex-bold'>(E)</span>\ 30