Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
173: | \[{3^{173}-1\over2}\] | 347 × 762239 × 2125048865543<13> × 30985428700388045508959018054392810762033149280306907746766819<62> |