Base 28 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
57: | \[{28^{57}-1\over27}\] | 3 × 271 × 457 × 90403 × 21084187 × 62830837877749<14> × 5504044949138999959<19> × 4652032620781659567810280156291<31> |