Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 99: | \[{4^{99}-1\over3}\] | 32 × 7 × 19 × 23 × 67 × 73 × 89 × 199 × 683 × 5347 × 20857 × 153649 × 599479 × 33057806959<11> × 242099935645987<15> |