- To sieve for all the twin primes less than 6000,

fill an array, J, of size 1000 with the integers 1 to 1000.

For k = 1 to 1000

J(k) = 0

next k

Then for m = 1 to 120, and n = m to 120

calculate

d0 = 6 m n - m - n

d1 = 6 m n + m - n

d2 = 6 m n - m + n

d3 = 6 m n + m + n

if d0 is between 1 and 1000, set J(d0) = 0

if d1 is between 1 and 1000, set J(d1) = 0

if d2 is between 1 and 1000, set J(d2) = 0

if d3 is between 1 and 1000, set J(d3) = 0

Then for any positive integer, G, still in the array,

6G-1 and 6G+1 are prime.

Illustration for smaller range.

6 * 1 * 1 - 1 - 1 = 4

1, 2, and 3 are skipped.

so 6 * 1 -1 = 5 and 6 * 1 + 1 = 7 are twin primes.

6*2-1 = 11 and 6*2+1=13 are twin primes

6*3-1 = 17 and 6 * 3 + 1 = 19 are twin primes.

6*1*1+1-1 = 6

5 is skipped.

so 6 * 5 -1 and 6 * 5 + 1 are twin primes.

6 * 1*1 + 1 + 1 = 8

7 is skipped.

6 * 7 -1 = 41 and 6 * 7 + 1 = 43 are twin primes.

etc.

Kermit

kermit@... - That particular sieve has been around since (at least)

January of 2000 when it was posted by Maria Suzuki in

the American Mathematical Monthly journal.

Which types of primes do you get when you replace the

6 with other numbers? E.g., 4mn +/- m +/- n. Can

other prime sieves be written in this (or a similar)

form successfully?

Joseph.

--- Kermit Rose <kermit@...> wrote:

> To sieve for all the twin primes less than 6000,

__________________________________

>

> fill an array, J, of size 1000 with the integers 1

> to 1000.

>

>

> For k = 1 to 1000

> J(k) = 0

> next k

>

>

> Then for m = 1 to 120, and n = m to 120

>

> calculate

>

> d0 = 6 m n - m - n

>

> d1 = 6 m n + m - n

>

> d2 = 6 m n - m + n

>

> d3 = 6 m n + m + n

>

>

> if d0 is between 1 and 1000, set J(d0) = 0

>

> if d1 is between 1 and 1000, set J(d1) = 0

>

> if d2 is between 1 and 1000, set J(d2) = 0

>

> if d3 is between 1 and 1000, set J(d3) = 0

>

>

> Then for any positive integer, G, still in the

> array,

>

>

> 6G-1 and 6G+1 are prime.

>

>

> Illustration for smaller range.

>

>

> 6 * 1 * 1 - 1 - 1 = 4

>

> 1, 2, and 3 are skipped.

>

> so 6 * 1 -1 = 5 and 6 * 1 + 1 = 7 are twin primes.

>

> 6*2-1 = 11 and 6*2+1=13 are twin primes

>

> 6*3-1 = 17 and 6 * 3 + 1 = 19 are twin primes.

>

>

> 6*1*1+1-1 = 6

>

> 5 is skipped.

>

>

> so 6 * 5 -1 and 6 * 5 + 1 are twin primes.

>

>

> 6 * 1*1 + 1 + 1 = 8

>

> 7 is skipped.

>

> 6 * 7 -1 = 41 and 6 * 7 + 1 = 43 are twin primes.

>

>

> etc.

>

>

>

> Kermit

> kermit@...

>

>

Yahoo! for Good - Make a difference this year.

http://brand.yahoo.com/cybergivingweek2005/ - From: Joseph Moore

Date: 12/30/05 14:51:01

To: Kermit Rose; primenumbers@yahoogroups.com

Subject: Re: [PrimeNumbers] A sieve for twin primes

That particular sieve has been around since (at least)

January of 2000 when it was posted by Maria Suzuki in

the American Mathematical Monthly journal.

Which types of primes do you get when you replace the

6 with other numbers? E.g., 4mn +/- m +/- n. Can

other prime sieves be written in this (or a similar)

form successfully?

Joseph.

*****************

From Kermit Rose

kermit@...

4 m n + m + n and

4 m n - m - n

sieves out all numbers which generate 4 D + 1.

4 m n + m - n

and

4 m n - m + n

sieves out all numbers which generate 4 D - 1.

In general

A m n + m + n and

A m n - m - n

sieves out all numbers which generate 4 D + 1.

[Non-text portions of this message have been removed]