Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 194: | \[{4^{194}-1\over3}\] | 5 × 389 × 971 × 1553 × 3881 × 4657 × 5821 × 11447 × 31817 × 3555339061 × 4959325597<10> × 394563864677<12> × 17637260034881<14> × 1100876018364883721<19> × 13842607235828485645766393<26> |