Base 3 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
251: | \[{3^{251}-1\over2}\] | 503 × 5894996162509148852365257446042626007<37> × 96461370326140480137275742594590102875331031471807256393566286296975030226677613<80> |