Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 205: | \[{4^{205}-1\over3}\] | 11 × 31 × 83 × 13367 × 2940521 × 164511353 × 8831418697<10> × 70171342151<11> × 3655725065508797181674078959681<31> × 2125820563389437533390243893834597846757304863651<49> |