Base 18 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 91: | \[{18^{91}-1\over17}\] | 79 × 449 × 521 × 8009 × 21841 × 80207 × 29759719289<11> × 107888439023<12> × 119941938141663914560035192594531172177434180409487272285332931752751273<72> |