Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 83: | \[{20^{83}-1\over19}\] | 27817851030769<14> × 2871487521092731391<19> × 414249085636225553185611071<27> × 1538310379327087356765985018066468033557956350069<49> |