On Fri, Sep 5, 2014 at 3:49 PM, Seymore4Head <Seymore4Head@hotmail.invalid> wrote: > I am sure this has already been done, but after it was pointed out > that you don't need to test for any number that multiplies by 2 it > made me think again. > > If you start with the list [3,5,7] and step through the list of all > remaining odd numbers (step 2), and start appending numbers that won't > divide by numbers already appended in the list, that would seem like a > pretty efficient way to find all prime numbers.
Indeed, this type of algorithm is known as a sieve. For a (literally) classical example, see http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes It's a nice way to find all the prime numbers up to a given limit, or it can be modified to run indefinitely high, but it's not very efficient for determining the primality of a single number. -- https://mail.python.org/mailman/listinfo/python-list
