Base 15 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 75: | \[{15^{75}-1\over14}\] | 11 × 61 × 241 × 4931 × 20101 × 46751 × 39225301 × 316091724098401<15> × 7112705843777290751<19> × 17402794883183351929087891501<29> |