Base 5 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 99: | \[{5^{99}-1\over4}\] | 19 × 31 × 199 × 829 × 143551 × 1731511 × 12207031 × 386478495679<12> × 22542470482159<14> × 153560376376050799<18> |