Base 8 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 221: | \[{8^{221}-1\over7}\] | 79 × 103 × 1327 × 2143 × 8191 × 11119 × 47737 × 121369 × 131071 × 1817023253798585112376955621635919346759818823715057<52> × 2365454398418399772605086209214363458552839866247069233<55> × 794848656730261183699896604513541946085000444947963571261039<60> |