Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 291: | \[{4^{291}-1\over3}\] | 3 × 7 × 971 × 1553 × 11447 × 25609 × 31817 × 272959 × 2065304407 × 5434876633<10> × 5636963037465601<16> × 581546606903256979<18> × 1100876018364883721<19> × 99695503427255026561<20> × 13842607235828485645766393<26> × 1170711644777651877659556633665719<34> |