Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 248: | \[{4^{248}-1\over3}\] | 5 × 17 × 257 × 5581 × 8681 × 8929 × 49477 × 290657 × 384773 × 715827883 × 2147483647 × 3770202641 × 1141629180401976895873<22> × 197107422273014301919781414466039325387889623676342705850752210599969<69> |