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; sequence A056725 in OEIS. Search limit given is the highest n searched, however, there is a gap from 230k ≤ n ≤ 1M.

History

• 2016-09-19: Found n = 1009567, P. Kurtovic
• 2011-01-07: Found n = 383643, D. Broadhurst
• 2010-12-19: Found n = 364521, D. Broadhurst
• 2010-11-05: Found n = 260253, D. Broadhurst
• 2010-11-09: Found n = 223871, D. Broadhurst
• 2010-11-04: Found n = 212903, D. Broadhurst
• 2004-01-21: Found n = 107663, J. Sun
• 2000-12-10: Found n = 48051, H.Dubner
• 2002-01-23: Found n = 41917, E. J. Sorensen
• 2000-10-27: Found n = 41475, D. Augustin
• 1994-12-01: Found n = 11143, H.Dubner
• 1994-10-01: Found n = 9631, H.Dubner
• 1994-10-01: Found n = 8415, H.Dubner
• ?: Found n = 935, Wilson

External links

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