Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 71: | \[{20^{71}-1\over19}\] | 201161092255316201234202042361<30> × 61777752739108975259079961779208763786873373427879250247440461<62> |