Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 122: | \[{4^{122}-1\over3}\] | 5 × 733 × 1709 × 3456749 × 368140581013<12> × 667055378149<12> × 768614336404564651<18> × 2305843009213693951<19> |