If we letf(n) denote the sum of all the positive divisors of the integer n, how many intergers i exist such that 1 <= i <= 2010 and \(f(i) = i + 1\)?
If f(i) = i + 1, the only divisors of i are 1 and i. That means i is a prime. You can calculate the number of primes in the given range for your answer.
