Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 220: | \[{4^{220}-1\over3}\] | 52 × 112 × 17 × 23 × 31 × 41 × 89 × 353 × 397 × 683 × 881 × 2113 × 2971 × 3191 × 61681 × 109121 × 148721 × 201961 × 48912491 × 2931542417 × 3404676001 × 415878438361<12> × 3630105520141<13> × 11035465708081<14> × 2546717317681681<16> |