Base 31 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 42: | \[{31^{42}-1\over30}\] | 25 × 3 × 73 × 19 × 43 × 211 × 331 × 6301 × 11971 × 71821 × 917087137 × 2813432694367<13> × 550469850411853<15> |