Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 226: | \[{4^{226}-1\over3}\] | 5 × 227 × 3391 × 23279 × 48817 × 58309 × 65993 × 1868569 × 2362153 × 636190001 × 1066818132868207<16> × 491003369344660409<18> × 15079116213901326178369<23> × 10384593717069655112945804582584321<35> |