Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
215: | \[{3^{215}-1\over2}\] | 112 × 431 × 8477881 × 380808546861411923<18> × 14491125481091320910774351<26> × 781053905037712555192394595228515676273221687831<48> |