Naive Parallel Prime Numbers Sieve in Erlang

The semi naive version checks only the numbers of the form 6n + 1 and 6n - 1 because all other numbers (6n + 2, 6n + 3, 6n + 4, 6n) are divided by 2 or 3.

Here is the code: https://gist.github.com/pavanky/9053387

Here are the results:

>$ python isprime.py

>isprime_6k @ 100 5.08 1.54

>isprime_sv @ 100 10.47 2.09

>isprime_6k @ 1000 11.94 2.23

>isprime_sv @ 1000 30.83 3.91

>isprime_6k @ 10000 33.78 3.3

>isprime_sv @ 10000 96.45 7.06

sv is the sieve version 6k is the semi naive version I mentioned. The first number is the (average) number of comparisons if the number is prime. The second number is the (average) number of comparisons if the number is not prime.

It looks like the sieve version is doing a much larger number of comparisons as the numbers get larger. Please let me know if I have done any mistakes in the coding. I did this fairly quickly and need more eyes to double check.