Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 305: | \[{4^{305}-1\over3}\] | 11 × 31 × 1831 × 2441 × 4271 × 270841 × 331841 × 484074637694471<15> × 768614336404564651<18> × 2305843009213693951<19> × 31347559232075126851<20> × 364371848053973128400380293624417256758401<42> × 247054336699552168887961800292921715571154497761<48> |