fresinha12 wrote:

yea but isnt 1 a factor and thus we cant count it as f(n)..

say n=3..Factors are 1 and 3..numbers less than 3 that are not factors of 3 are ..1 i.e 2..i didnt count 1 since 1 is already a factor of 3..

The question doesn't ask you to count how many numbers less than n are not divisors of n. It asks how many numbers less than n do not share any divisors (besides 1) with n, which is a different thing. 12 is not a divisor of 18, but 12 does share divisors with 18. In any case, you definitely must count one here: for any n>1, one will be an positive integer less than n which does not share any divisors with n (besides 1), and f(n) counts all such positive integers.

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