Williams prime MM 5

Definition

Williams primes (b-1)•bⁿ-1 with b = 5 (primes of the form 4•5ⁿ-1, n ≥ 1).

Prime for n

1, 3, 9, 13, 15, 25, 39, 69, 165, 171, 209, 339, 2033, 6583, 15393, 282989, 498483, 504221, 754611, 864751

Search range

n = 1000000 (2019-04-04)

History

Date	Remark
2019-04-04	Checked to n = 1000000, Karsten Bonath
2019-02-23	found n = 864751, Karsten Bonath
2019-01-27	found n = 754611, Karsten Bonath
2018-12-24	found n = 504221, Karsten Bonath
2018-12-23	found n = 498483, Karsten Bonath
2018-12-06	Checked to n = 1 - 321000, found n = 282989, Karsten Bonath
2007-20-12	Checked to n = 200000, Geoff Reynolds
2007-07-13	Checked to n = 110000, Geoff Reynolds
2006-08	Found n = 15393, antiroach
1981	Checked to n = 500, found n = 1 ... 339, H. C. Williams

External links

• Williams number
• Thread at MersenneForum
• The sequence A046865 in OEIS