Williams primes of the form 9•10n-1

Current data

Base : 10 Count : 21 Max n : 1,030,000 Date : 2019-01-29

1, 3, 7, 19, 29, 37, 93, 935, 8415, 9631, 11143, 41475, 41917, 48051, 107663, 212903, 223871, 260253, 364521, 383643, 1009567

Remarks :

These primes are Near-repdigit numbers; Search limit given at sequence A056725 in OEIS is the highest n searched, however, there is a gap from 230k ≤ n ≤ 1M.

History

• 2019-01-29: Checked n = 1000000  -  10300007, Predrag Kurtovic
• 2016-09-19: Found n = 1009567, Predrag Kurtovic
• 2011-04-17: Checked n = 100000  -  230000, Gary Barnes
• 2011-01-07: Found n = 383643, David Broadhurst
• 2010-12-19: Found n = 364521, David Broadhurst
• 2010-11-05: Found n = 260253, David Broadhurst
• 2010-11-09: Found n = 223871, David Broadhurst
• 2010-11-04: Found n = 212903, David Broadhurst
• 2006-10-30: Checked to n = 5000, Hugo Platzer
• 2004-01-21: Found n = 107663, Jiong Sun
• 2002-01-23: Found n = 41917, Eric J. Sorensen
• 2000-12-10: Found n = 48051, Harvey Dubner
• 2000-10-27: Found n = 41475, Dirk Augustin
• 1994-12-01: Found n = 11143, Harvey Dubner
• 1994-10-01: Found n = 9631, Harvey Dubner
• 1994-10-01: Found n = 8415, Harvey Dubner
• ?: Found n = 935, Robert G. Wilson

External links

• Factorizations for n ≤ 300 & search history from M. Kamada