Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 203: | \[{21^{203}-1\over20}\] | 43 × 59 × 631 × 3319 × 7309 × 576986089 × 1103704099 × 246763300513<12> × 139184658492559<15> × 687613372491653<15> × 960400283241933241<18> × 7690755329903725696668350079937171<34> × 951363762097381671218323905908798973133<39> × 203252608875340597411995971323532717433013<42> × 1542529703094677555311359180186347885870250840973897401657811561<64> |