Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
142: | \[{21^{142}-1\over20}\] | 2 × 11 × 493509073 × 826880829487<12> × 172132091765842074983<21> × 6912925952086714539251625713<28> × 110556144297525239244017467747224789359885811468762753179<57> × 2409031482389671650882277254771562219466455949802660831413381<61> |