Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 129: | \[{4^{129}-1\over3}\] | 3 × 7 × 431 × 1033 × 9719 × 2099863 × 1591582393 × 2932031007403<13> × 15686603697451<14> × 11053036065049294753459639<26> |