Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 152: | \[{4^{152}-1\over3}\] | 5 × 17 × 229 × 257 × 457 × 1217 × 27361 × 148961 × 174763 × 524287 × 525313 × 24517014940753<14> × 69394460463940481<17> × 11699557817717358904481<23> |