February 18, 2005--Less than a year after the 41st Mersenne prime was reported (MathWorld headline news: June 1, 2004), Great Internet Mersenne Prime Search (GIMPS) project organizer George Woltman is reporting in a Feb. 18 email to the GIMPS mailing list that a new Mersenne number has been flagged as prime and reported to the project's server.
| # | p | digits | year | discoverer (reference) |
| 1 | 2 | 1 | antiquity | |
| 2 | 3 | 1 | antiquity | |
| 3 | 5 | 2 | antiquity | |
| 4 | 7 | 3 | antiquity | |
| 5 | 13 | 4 | 1461 | Reguis 1536, Cataldi 1603 |
| 6 | 17 | 6 | 1588 | Cataldi 1603 |
| 7 | 19 | 6 | 1588 | Cataldi 1603 |
| 8 | 31 | 10 | 1750 | Euler 1772 |
| 9 | 61 | 19 | 1883 | Pervouchine 1883, Seelhoff 1886 |
| 10 | 89 | 27 | 1911 | Powers 1911 |
| - | --- | --- | --- | [**table abbreviated by entries 11-35**] |
| 36 | 2976221 | 895832 | 1997 | Spence, Woltman, GIMPS (Devlin 1997) |
| 37 | 3021377 | 909526 | 1998 | Clarkson, Woltman, Kurowski, GIMPS |
| 38 | 6972593 | 2098960 | 1999 | Hajratwala, Woltman, Kurowski, GIMPS |
| 39 | 13466917 | 4053946 | 2001 | Cameron, Woltman, GIMPS (Whitehouse 2001, Weisstein 2001ab) |
| 40? | 20996011 | 6320430 | 2003 | Shafer, GIMPS (Weisstein 2003ab) |
| 41? | 24036583 | 7235733 | 2004 | Findley, GIMPS (Weisstein 2004) |
| 42? | 25964951 | 7816230 | 2005 | GIMPS |
| 43? | 30402457 | 9152052 | 2005 | GIMPS |
Caldwell, C. K. "The Largest Known Primes."
http://www.utm.edu/research/primes/largest.html
GIMPS: The Great Internet Mersenne Prime Search.
http://www.mersenne.org
GIMPS: The Great Internet Mersenne Prime Search Status.
http://www.mersenne.org/status.htm
Weisstein, E. W. "MathWorld Headline News: 40th Mersenne Prime Announced."
Dec. 2, 2003.
http://mathworld.wolfram.com/news/2003-12-02/mersenne
Weisstein, E. W. "MathWorld Headline News: 41st Mersenne Prime Announced."
Jun. 1, 2004.
http://mathworld.wolfram.com/news/2004-06-01/mersenne
Woltman, G. "New Mersenne Prime?!" Message to The Great Internet Mersenne Prime Search List. Feb. 18, 2005.