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The computer programs used

For the most time-consuming number crunching, we have to balance the effectiveness of two programs, namely Paul Jobling's "NewPGen" and Jean Penne and George Woltman's "LLR".

NewPGen is the sieving program we use to check all 321 candidates for small divisors. For example, on testing for divison by 5, a quarter of all candidates will be removed as not prime. However it becomes increasingly time-consuming to find new divisors of any of the candidates and we switch over to the program LLR which will, at the current level of testing, determine the primailty of any remaining candidate in a few hours.

As of 16th March 2006, after three years of sieving on many computers, we have reached the level where it is now quicker to just run LLR on all remaining prime candidates.

Early 2007 update: due to improved software we are able to sieve a little further with srsieve.

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