Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 233: | \[{4^{233}-1\over3}\] | 467 × 1399 × 27961 × 135607 × 622577 × 116868129879077600270344856324766260085066532853492178431<57> × 352369374013660139472574531568890678155040563007620742839120913<63> |