Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 320: | \[{4^{320}-1\over3}\] | 52 × 11 × 17 × 31 × 41 × 257 × 641 × 61681 × 65537 × 274177 × 286721 × 414721 × 3602561 × 6700417 × 446960641 × 4278255361 × 96645260801<11> × 44479210368001<14> × 67280421310721<14> × 3442404051886487041<19> × 94455684953484563055991838558081<32> × 2715862005931406599419575483412481<34> |