For which positive integers p is 2p-1 a prime number?

Such prime numbers are called now-a-days Mersenne Primes and p is called its (prime) exponent.
A table ordered by discovery date follows:

Rank exponent p discovery date discoverer (credited persons) needed real time to prove supporting help
1 2< 0
2 3< 0
3 5< 0
4 7< 0
5 131456
6 171588Pietro Cataldi
7 191588Pietro Cataldi
8 311772Leonhard Euler
12 1271876Francois Edouard A. Lucas
9 611883Ivane M. Pervouchine
10 891911R. E. Powers
11 1071914R. E. Powers
13 5211952-01-30 Raphael M. Robinson~ 80 secSWAC
14 6071952-01-30 Raphael M. Robinson~ 2 minSWAC
15 12791952-06-25 Raphael M. Robinson13.5 minSWAC
16 22031952-10-07 Raphael M. Robinson~ 55 minSWAC
17 22811952-10-09 Raphael M. Robinson1 hourSWAC
18 32171957-09-08 Hans Riesel5.5 hoursBESK
19 42531961-11-03 Alexander Hurwitz & John L. Selfridge~ 50 min IBM 7090
20 44231961-11-03 Alexander Hurwitz & John L. Selfridge50 min IBM 7090
21 96891963-05-11 Donald B. Gillies83 minILLIAC II
22 99411963-05-16 Donald B. Gillies90 minILLIAC II
23 112131963-06-02 Donald B. Gillies135 minILLIAC II
24 199371971-03-04 Bryant Tuckerman35 minIBM 360/91
25 217011978-10-30 Landon Curt Noll & Laura Nickel7h 40m 20sCDC Cyber 174
26 232091979-02-09 Landon Curt Noll & Laura Nickel8h 39m 37s CDC Cyber 174
27 444971979-04-08 Harry Nelson & David Slowinski Cray 1
28 862431982-09-25 David Slowinski Cray 1
30 1320491983-09-19 David Slowinski Cray X-MP
31 2160911985-09-01 David Slowinski Cray X-MP/24
29 1105031988-01-28 Walt Colquitt & Luke Welsh 686 secNEC SX/2
32 7568391992-04-01 David Slowinski & Paul Gage ~ 16 hours Cray-2
33 8594331994-02-01 David Slowinski & Paul Gage 7.2 hours Cray C90
34 12577871996-09-03 David Slowinski & Paul Gage ~ 6 hoursCray T94
35 13982691996-11-23 Joel Armengaud, Woltman, et. al. 88 hours 90 MHz Pentium PC
36 29762211997-09-01 Gordon Spence, Woltman, et. al. 15 days100 MHz Pentium PC
37 30213771998-01-27 Roland Clarkson, Woltman, Kurowski et. al. 46 days200 MHz Pentium PC
38 69725931999-06-01 Nayan Hajratwala, Woltman, Kurowski et. al. 111 days350 MHz Pentium II IBM Aptiva PC
39134669172001-11-14 Michael Cameron, Woltman, Kurowski et. al. 45 days800 MHz AMD T-Bird PC
40209960112003-11-17 Michael Shafer, Georg Woltman, Scott Kurowski et. al. 19 days2 GHz Pentium 4 Dell Dimension PC
41240365832004-05-15 Josh Findley, Georg Woltman, Scott Kurowski et. al. 14 days2.4 GHz Pentium 4 PC
42259649512005-02-18 Martin Nowak, Georg Woltman, Scott Kurowski et. al. 50 days2.4 GHz Pentium 4 PC
43304024572005-12-15 Curtis Cooper and Steven Boone, Georg Woltman, Scott Kurowski et. al. ~ 50 daysPC network of 700 PC
44325826572006-09-04 Curtis Cooper and Steven Boone, Georg Woltman, Scott Kurowski et. al. ~ 9 monthsPC network of 700 PC
47431126092008-08-23 Edson Smith, Georg Woltman, Scott Kurowski et. al. 35 days 2.4 GHz Intel Core 2 Duo E6600 Dell Optiplex 745 PC
45371566672008-09-06 Hans-Michael Elvenich, Georg Woltman, Scott Kurowski et. al. 218 days 2.83 GHz Intel Core 2 Duo E8300 PC
46426438012009-04-12 Odd Magnar Strindmo, Georg Woltman, Scott Kurowski et. al. 29 days 3.0 GHz Intel Core 2 PC
48578851612013-01-25 Curtis Cooper, Georg Woltman, Scott Kurowski et. al. 39 days3.0 GHz Intel Core2 Duo E8400 CPU PC
49742072812016-01-07 Curtis Cooper, Georg Woltman, Scott Kurowski et. al. 31 days3.6 GHz Intel I7-4790 CPU PC
50772329172017-12-26 Jonathan Pace, Georg Woltman, Scott Kurowski et. al. 6 days3.3 GHz Intel I5-6600 CPU PC
51825899332018-12-07 Patrick Laroche, Georg Woltman, Scott Kurowski et. al. 12 days2.0 GHz Intel I5-4590T CPU PC
521362798412024-10-12 Luke Durant, Georg Woltman, Scott Kurowski et. al. NVIDIA A100 GPU
time rangecountwhohowwhyimportants
Antiquity 4 philosophs (?) reflecting by mind philosophy / culture discovery of meaning
Middle Ages 3 hobby numberists trial divisions by hand calculations culture/fashion in Italy disproof of tradition 211-1 must be prime
18-th century until mid 20-th century (~ 220 years) 5 first professional mathematicians hand calculations (Lucas sequences) arise of scientific precise culture important theoretical insights achieved
1951-1954 5 a mathematician Lucas-Lehmer test used scientific culture first reliable electronic calculators
1954 - 1979 (27 years) 9 different mathematicians LL-test on date-typical computers proud of record breaking
1979 - 1996 (17 years) 8 mainly a single programmer LL-test on special vector-computers (Cray) proud of record breaking (making history)
January 1996 - October 2024 (28 years) 17 mainly one, later two, fixed programmer(s) and random people coordinated distributed search on common computers for interested people (LL-test with FFT-multiplication) proud of record breaking (making history) social/info culture (GIMPS)
October 2024 - today (1.5 years) 1 one expert GPU-programmer thousands of GPUs on distibuted servers (LL-test with FFT-multiplication on GPUs) proud of record breaking (making history)

Historical information about Mersenne number discoveries before 1963.
More details on History of Mersenne Primes
GIMPS (Distributed search for Mersenne Primes


Achim Flammenkamp
2026-02-20 12:04 UTC+1