Base 15 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 221: | \[{15^{221}-1\over14}\] | 53 × 157483 × 16655159 × 1045002649 × 6734509609<10> × 6019473617095910810405643116554900751260078533677264768122817030629284192746685445376640615610452928703392579361688186623190084447488357003712701401041577633906917339124773712456435176733943548566173859623213566879398193359361<226> |