Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 212: | \[{4^{212}-1\over3}\] | 5 × 17 × 107 × 6361 × 69431 × 15358129 × 20394401 × 586477649 × 1692645313 × 28059810762433<14> × 1801439824104653<16> × 10920513604018498900801<23> × 20946001591429012199281424246257<32> |