Base 13 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 77: | \[{13^{77}-1\over12}\] | 23 × 419 × 859 × 18041 × 5229043 × 624958606550654822293<21> × 10138828706452319901511087969019211193701892213<47> |