Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 303: | \[{4^{303}-1\over3}\] | 3 × 7 × 607 × 112102729 × 7432339208719<13> × 341117531003194129<18> × 845100400152152934331135470251<30> × 19112684214957755703306290219340140859813072336321619<53> × 1512768222413735255864403005264105839324374778520631853993<58> |