Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
256: | \[{3^{256}-1\over2}\] | 29 × 5 × 17 × 41 × 193 × 257 × 275201 × 21523361 × 138424618868737<15> × 926510094425921<15> × 3913786281514524929<19> × 153849834853910661121<21> × 1716841910146256242328924544641<31> |