Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 177: | \[{4^{177}-1\over3}\] | 3 × 7 × 2833 × 13099 × 37171 × 179951 × 184081 × 1824726041 × 27989941729<11> × 3203431780337<13> × 4453762543897<13> × 1898685496465999273<19> × 9213624084535989031<19> |