Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 155: | \[{4^{155}-1\over3}\] | 11 × 312 × 311 × 11161 × 11471 × 73471 × 715827883 × 2147483647 × 4649919401<10> × 18158209813151<14> × 5947603221397891<16> × 29126056043168521<17> |