Base 28 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 69: | \[{28^{69}-1\over27}\] | 3 × 47 × 139 × 271 × 277 × 224727078564911869<18> × 1517655145813456319033978812579<31> × 527264972197836529557199851838274216840527<42> |