Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 323: | \[{4^{323}-1\over3}\] | 647 × 7753 × 43691 × 131071 × 174763 × 524287 × 17795830908608814443<20> × 39044358788825633753<20> × 3211586054639813621611<22> × 6319957642033539607139<22> × 2065255878519475622261353<25> × 1269639828454588763972435091645259869185718465075550865591017<61> |