Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 141: | \[{4^{141}-1\over3}\] | 3 × 7 × 283 × 2351 × 4513 × 1681003 × 13264529 × 4375578271<10> × 35273039401<11> × 111349165273<12> × 165768537521<12> × 646675035253258729<18> |