Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 247: | \[{3^{247}-1\over2}\] | 1597 × 14327 × 363889 × 797161 × 50427403417<11> × 85336889516918333646696709<26> × 123634978316170336137330788562343247835605751304272686452015331<63> |