Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
206: | \[{4^{206}-1\over3}\] | 5 × 41201 × 17325013 × 520379897 × 2550183799 × 415141630193<12> × 473000157711296729<18> × 8142767081771726171<19> × 3976656429941438590393<22> × 117070097457656623005977<24> |