Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 88: | \[{4^{88}-1\over3}\] | 5 × 17 × 23 × 89 × 257 × 353 × 397 × 683 × 2113 × 229153 × 119782433 × 2931542417 × 43872038849<11> |