happen, but the project found a missed prime in their doublecheck work: http://www.mersenneforum.org/showthread.php?t=4863
DOUBLE CHECK UNCOVERS 9TH PRIME!
(posted by louis helm) Wednesday, 19 Oct 2005
4847 * 2^3321063 + 1 is prime! This is great news as k=4847 was a relatively dense series that required more tests in a given range than the average k. The prime was discovered at 10:50PM EST on October 15th by Richard Hassler, a long-time user who has been crunching SB since August 2003.
You may notice that this prime is smaller than the last few discoveries we've made (only 999744 digits [decimal expansion]). That's because this prime was uncovered by a double check. Hopefully those of us disappointed by the artificial slowdown that double checks have caused recently are pleased that it resulted in a new discovery so quickly. We're working to correct the scoring system so that these tests are worth as much per amount of computation as larger ones. Until we do, keep in mind that although the scoring has temporarily decreased, the ease of finishing a test has gone up which does improve your chances of actually finding a prime.
Congratulations to the whole SB community! These primes are rare so take a moment to appreciate all the hard work that goes into producing them. Each SB participant helped do their part to increase the bounds of human knowledge with this discovery. Be proud of your accomplishment! 9 down -- 8 to go.