Counting primes using the Sieve of Eratosthenes in R

Sieve of Eratosthenes.R

# The Sieve of Eratosthenes

# Given a number greater than zero this function will return a list of primes between 2 and the number given as argument.
sieveOfEratosthenes <- function(num){
  values <- rep(TRUE, num)
	values[1] <- FALSE
	prev.prime <- 2
	for(i in prev.prime:sqrt(num)){
		values[seq.int(2 * prev.prime, num, prev.prime)] <- FALSE
		prev.prime <- prev.prime + min(which(values[(prev.prime + 1) : num]))
	}
	return(which(values))
}

sieveOfEratosthenes(2000)

length(sieveOfEratosthenes(2000)) # 303