Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 148: | \[{4^{148}-1\over3}\] | 5 × 17 × 149 × 223 × 593 × 1777 × 25781083 × 184481113 × 231769777 × 616318177 × 20988936657440586486151264256610222593863921<44> |