Williams primes base 5

 Reserved! This sequence is currently reserved by: Karbon

Definition

Primes of the form $4 \cdot {5^n{-}1}$.

Primes for n

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

Search range

321000 (2018-12-07)

History

Date Remark
2018-12-07 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 Found n=1 ... 339, checked to n=500, H. C. Williams