Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 185: | \[{4^{185}-1\over3}\] | 11 × 31 × 223 × 1481 × 1777 × 25781083 × 28136651 × 616318177 × 1587855697992791<16> × 7248808599285760001152755641<28> × 778429365397887608540618330873281<33> |