Base 31 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 55: | \[{31^{55}-1\over30}\] | 5 × 112 × 23 × 397 × 617 × 17351 × 150332843 × 167767051 × 236661696642275153056980146191674776616380367693641<51> |