Base 18 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
63: | \[{18^{63}-1\over17}\] | 74 × 127 × 449 × 631 × 991 × 2143 × 34327 × 80207 × 1292257 × 156107192084257<15> × 6974796889885559915764172408527<31> |