Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| * 520: | \[{20^{520}-1\over19}\] | 3 × 7 × 11 × 41 × 53 × 61 × 131 × 251 × 401 × 521 × 937 × 2081 × 2549 × 2801 × 3121 × 3511 × 4421 × 90481 × 142559 × 148721 × 152381 × 160001 × 222361 × 502321 × 1961441 × 9690539 × 444665521 × 735408649 × 4470064171<10> × 144142570154831<15> × 4406613081041681<16> × 34458786390125761<17> × 26916259659749909489<20> × 4329520082233745656921<22> × 9929340931665117562081<22> × 628605693732325702045277<24> × [5510721632894987152685087783644833103088705293082182878263441136975717669454834930273901516272855719405358909604536485054255468404835422065846149713531062305779957687794118582459499233686392418993019673566923646285359414356291688198369802504353651518000916457092934605956251780578943225368328816814875624665643501480716418436177283133572319424220337245843032742554651649158946556556395014546735315614005804455863296846286397<424>] |