Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 163: | \[{20^{163}-1\over19}\] | 2609 × 39131523449<11> × 631612844763349<15> × 95429775858445039129131053586733157861653052516144458305918156705941649399697284182341073814660030767197158276193914366390169405269705059782924097489474263497273399505335900534859369<182> |