Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| * 261: | \[{21^{261}-1\over20}\] | 59 × 463 × 85775383 × 1103704099 × 246763300513<12> × 687613372491653<15> × 7826081384442721874824416529<28> × 13477015991023291802765110016390772920553907009<47> × [1357671238386020933838270424843315643602966928873181391507405546183548396007350791527897203351634533187623594722570113741792425655211715919077622740276490135953197495784409620482866764304832619976459828777311339621796516081<223>] |