Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 393: | \[2^{393}-1\] | 7 × 263 × 36093121 × 51118297 × 58352641 × 10350794431055162386718619237468234569<38> × 9833304614455302578430964280893955512223415028355534287<55> |