Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 239: | \[{4^{239}-1\over3}\] | 479 × 1913 × 5737 × 176383 × 340337 × 134000609 × 32605142983704221670173899<26> × 26537037220992112785174856161239437662001<41> × 7110008717824458123105014279253754096863768062879<49> |