Skip to content / Đến nội dung
ThichHocToan.com

2015 AMC 12B Question 18

AMC12 · 2015 AMC 12B

Question 18

For every composite positive integer $n,$ define $r(n)$ to be the sum of the factors in the prime factorization of $n.$ For example, $r(50) = 12$ because the prime factorization of $50$ is $2 \cdot 5^2,$ and $2 + 5 + 5 = 12.$ What is the range of the function $r,$ $\{r(n) : n \text{ is a composite positive integer}\}?$
  1. the set of positive integers
  2. the set of composite positive integers
  3. the set of even positive integers
  4. the set of integers greater than $3$
  5. the set of integers greater than $4$