PrimeGrid 321 Prime Search

Purpose

PrimeGrid 321 Prime Search is an extension of Paul Underwood’s 321 Search since 2008.

PrimeGrid has added the 3•2ⁿ+1 form to the search and will be testing both 3•2ⁿ-1 and 3•2ⁿ+1 forms beyond n=5000000.

Status

• The current n_max = 22,021,811 as of 2024-10-13 (see Multi Reservation 22).
• 321 Prime Search status at PrimeGrid

Primes found

• 2023-07-06: Riesel 3•2^20928756-1, Arno Lehmann
• 2022-03-24: Riesel 3•2^18924988-1, Frank Matillek (Official announcement)
• 2022-01-18: Riesel 3•2^18196595-1, (Anonymous) (Official announcement)
• 2021-09-06: Riesel 3•2^17748034-1, Marc Wiseler (Official announcement)
• 2021-01-20: Riesel 3•2^16819291-1, Rudi Tapper (Official announcement)
• 2020-10-25: Proth 3•2^16408818+1, James Scott Brown (Official announcement)
• 2015-06-23: Riesel 3•2^11895718-1, Michael Schulz (Official announcement)
• 2015-03-13: Riesel 3•2^11731850-1, Karsten Klopffleisch (Official announcement)
• 2014-11-22: Riesel 3•2^11484018-1, Serhiy Gushchak (Official announcement)
• 2012-01-14: Proth 3•2^10829346+1, Sai Yik Tang (Official announcement)
• 2011-02-21: Proth 3•2^7033641+1, Michael Herder (Official announcement)
• 2010-04-24: Riesel 3•2^6090515-1, David Mumper (Official announcement)
• 2009-04-03: Proth 3•2^5082306+1, Andy Brady (Official announcement)
• 2008-08-11: Proth 3•2^2291610+1, Thomas Wolfram (Official announcement)
• 2008-03-23: Riesel 3•2^4235414-1, Dylan Bennett (Official announcement)

Total: 15 primes found

History

• Milestones

See also

• 321 Search

External links

• 321 Prime Search - PrimeGrid forums
• History of 321 Search at MersenneForum
• Overview at 321 Search at MersenneForum

PrimeGrid

Miscellaneous

Main

Subprojects

Type Proth : 321 Prime Search 27121 Prime Search Proth Prime Search Proth Prime Search Extended Proth Mega Prime Search Type Sierpiński : Seventeen or Bust Extended Sierpiński Project Prime Sierpiński Problem Sierpiński base 5 Type Riesel : The Riesel Problem Riesel base 5 Type Fermat : Generalized Fermat Prime Search b216+1 b217+1 b218+1 b219+1 b220+1 b221+1 b222+1 Fermat Divisor Search Type Cullen/Woodall : Cullen Prime Search Woodall Prime Search Generalized Cullen Prime Search Type Others : AP27 Search Sophie Germain Search Wieferich and Wall-Sun-Sun Prime Search

Completed

GFN b215+1

Others