Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 391: | \[{4^{391}-1\over3}\] | 47 × 2347 × 37537 × 43691 × 131071 × 178481 × 1578859 × 2796203 × 194902553 × 291438334156037699<18> × 29111948248642861801<20> × 25806248225716242845491832244899635927231330561<47> × 2245714052771430777876143006786838979329549117936841<52> × 4735299062751047834629348947476766642710028552319600543<55> |