Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 259: | \[{4^{259}-1\over3}\] | 43 × 127 × 223 × 1777 × 25781083 × 616318177 × 2499285769 × 1456235596904319041738812533139<31> × 107636344217840413139193500838915409<36> × 21234370960880098806027750185552713706866970578963970119<56> |