Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 331: | \[{4^{331}-1\over3}\] | 5297 × 2983001129 × 7520796641<10> × 16937389168607<14> × 865118802936559<15> × 8530674250842274717434530683<28> × 1438390199144030563364806863704510189429516419097<49> × 298542624980197463613767215333569428005686468835821253721796682625551919<72> |