Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 113: | \[{4^{113}-1\over3}\] | 227 × 3391 × 23279 × 48817 × 65993 × 1868569 × 636190001 × 1066818132868207<16> × 491003369344660409<18> |