Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 193: | \[{4^{193}-1\over3}\] | 6563 × 13821503 × 35679139 × 1871670769 × 7455099975844049<16> × 1280761337388845898643<22> × 61654440233248340616559<23> × 14732265321145317331353282383<29> |