Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 147: | \[{4^{147}-1\over3}\] | 3 × 73 × 43 × 127 × 337 × 5419 × 748819 × 4363953127297<13> × 4432676798593<13> × 26032885845392093851<20> × 2741672362528725535068727<25> |