Base 18 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
50: | \[{18^{50}-1\over17}\] | 11 × 19 × 41 × 2711 × 9041 × 602401 × 738851 × 17254127651933924651<20> × 21162386787273369601<20> |