Question

how many positive integers n less than 1000,have the property that the number of positive integers less than n which are coprime to n,is exactly n/3?

Answer 1

24

Answer 2

In general the number of postive integers less then x, that have the property that the number of positive integers less then n which are coprime to n, is exactly n/3, is given exactly by $$\sum_{k\leq \log_3(x)}\log_2(\frac{x}{3^k})$$

Answer 3

Substitute $$x=1000$$ And you will get the desired result

Answer 4

can u explain that formula?

Answer 5

Yes.

Answer 6

tanx

Answer 7

Can you do somthing for me though

Answer 8

wat?

Answer 9

Stop using http://brilliant.org/

Answer 10

sorry,i can't