Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 199: | \[{4^{199}-1\over3}\] | 164504919713<12> × 4884164093883941177660049098586324302977543600799<49> × 267823007376498379256993682056860433753700498963798805883563<60> |