Base 28 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 56: | \[{28^{56}-1\over27}\] | 5 × 29 × 113 × 157 × 281 × 449 × 13007 × 23633 × 35771 × 614657 × 749729 × 4422461 × 54034289 × 213827041 × 1100860153 × 439840060577<12> |