Base 18 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 131: | \[{18^{131}-1\over17}\] | 263 × 4937129 × 583611289 × 83265325271<11> × 5429089043897<13> × 59305632978486649450720615586460322077911114394209<50> × 798745172959415696032317403216661106058706840191203912192586967699963207<72> |