Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 50: | \[{20^{50}-1\over19}\] | 3 × 7 × 11 × 61 × 101 × 151 × 251 × 1451 × 152381 × 1369801 × 7466201 × 46794901 × 1038193734970398415809901<25> |