Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 261: | \[{4^{261}-1\over3}\] | 32 × 7 × 19 × 59 × 73 × 233 × 523 × 1103 × 2089 × 4177 × 3033169 × 6929826139<10> × 9857737155463<13> × 96076791871613611<17> × 3453412901832690553<19> × 33563856450515702761<20> × 328017025014102923449988663752960080886511412965881<51> |