Base 15 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 83: | \[{15^{83}-1\over14}\] | 2158116330311<13> × 3220419108264156535849497113<28> × 424091160188578436595274724511088099915436894806250614687<57> |