Base 31 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 71: | \[{31^{71}-1\over30}\] | 17609 × 611127785361198601<18> × 642443809919609072204778169817<30> × 37141302977105581064921322418772202338727337015016057<53> |