$ cat primeSieveExample.go
package main

import (
    "fmt"
    "math"
    "runtime"
)

const target int64 = 60085147

// Start up a prime sieve generator
func Generate(ch chan<- int64) {
    var i int64
    for i = 2; ; i++ {
        ch <- i
    }
}

func Filter(in <-chan int64, out chan<- int64, prime int64) {
    for {
        i := <-in
        if i % prime != 0 {
            out <- i
        }
    }
}

func using_goroutines() int {
    runtime.GOMAXPROCS(40)

    var max_factor int64 = 0
    var prime int64;
    ch := make(chan int64)
    max_iter := math.Sqrt(float64(target))

    go Generate(ch)

    for float64(prime) < max_iter {
        prime = <-ch

        if target % prime == 0 {
            max_factor = prime
        }

        ch1 := make(chan int64)
        go Filter(ch, ch1, prime)
        ch = ch1
    }
    fmt.Printf("%d\n", max_factor)
    return 0
}

func main() {
    using_goroutines()
}
$ cat problem3.py
import math

#target = 600851475143
target = 60085147

def integer_generator():
	i = 2
	while True:
		yield i
		i += 1

def filter(int_stream, prime):
	for i in int_stream:
		if i % prime == 0:
			continue
		yield i

def main():
	ig = integer_generator()
	prime = ig.next()
	max_iter = math.sqrt(target)
	max_factor = 0

	while prime < max_iter:
		f = filter(ig, prime)
		prime = f.next()
		ig = f

		if target % prime == 0 and prime > max_factor:
			max_factor = prime

	print max_factor

if __name__ == "__main__":
	main()

$ go build primeSieveExample.go
$ time ./primeSieveExample
43

real	0m0.064s
user	0m0.188s
sys	0m0.008s
$ time python ./problem3.py
43

real	0m0.103s
user	0m0.093s
sys	0m0.009s