Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 407: | \[{4^{407}-1\over3}\] | 23 × 89 × 223 × 683 × 1777 × 3257 × 15467 × 25781083 × 616318177 × 2248206137 × 3068001817 × 25330067076999169<17> × 1826375940722234754636475033<28> × 42897689055449636582684640379732099<35> × 93189126452944019033888022519639331350438619<44> × 64374964789425759023795123420605218308370931223311543823123770088423<68> |