Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
82: | \[{20^{82}-1\over19}\] | 3 × 7 × 83 × 739 × 1723 × 824754607 × 35641617587<11> × 788985829969499330639<21> × 2490949949323610858879377601<28> × 19850094536448035972954342201<29> |