Base 18 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
78: | \[{18^{78}-1\over17}\] | 73 × 19 × 79 × 131 × 307 × 521 × 2081 × 4020180841 × 7424759473<10> × 29759719289<11> × 170258429679493134487<21> × 1412364383703504438982118048251<31> |