Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 69: | \[{20^{69}-1\over19}\] | 139 × 421 × 691 × 1381 × 119553964489<12> × 113317059163579<15> × 46266279097921483078651<23> × 887612944642122132741202450909<30> |