MathDB
Divisibility of a Factorial

Source:

January 14, 2009
factorial

Problem Statement

For how many positive integers n n less than or equal to 24 24 is n! n! evenly divisible by 1 \plus{} 2 \plus{} \dots \plus{} n? <spanclass=latexbold>(A)</span> 8<spanclass=latexbold>(B)</span> 12<spanclass=latexbold>(C)</span> 16<spanclass=latexbold>(D)</span> 17<spanclass=latexbold>(E)</span> 21 <span class='latex-bold'>(A)</span>\ 8\qquad <span class='latex-bold'>(B)</span>\ 12\qquad <span class='latex-bold'>(C)</span>\ 16\qquad <span class='latex-bold'>(D)</span>\ 17\qquad <span class='latex-bold'>(E)</span>\ 21