Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 178: | \[{21^{178}-1\over20}\] | 2 × 11 × 179 × 3357259 × 138348511207<12> × 330901808518637<15> × 27329974534657721237<20> × 265584888342742928831<21> × 1814250359778886183181<22> × 82607166715167534575509117058219<32> × 1719937817227174896868741057213630597485253956382680484361683645714455944660556942937263903929864448451087<106> |