Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 121: | \[{20^{121}-1\over19}\] | 257277256721<12> × 2431995161971<13> × 10778947368421<14> × 207460499909279296762540583487933439637201905299100245238682598870759408878141960495778332780218147735503696620877792011<120> |