Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 253: | \[{4^{253}-1\over3}\] | 232 × 47 × 89 × 683 × 4049 × 85009 × 178481 × 2796203 × 31797547 × 4103188409 × 81776791273<11> × 199957736328435366769577<24> × 44667711762797798403039426178361<32> × 2822551529460330847604262086149015242689<40> |