Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 153: | \[{4^{153}-1\over3}\] | 32 × 7 × 19 × 73 × 103 × 307 × 919 × 2143 × 2857 × 6529 × 11119 × 43691 × 123931 × 131071 × 26159806891<11> × 27439122228481<14> × 75582488424179347083438319<26> |