Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 161: | \[{4^{161}-1\over3}\] | 43 × 47 × 127 × 1289 × 178481 × 2796203 × 3188767 × 45076044553<11> × 14808607715315782481<20> × 8103467492759792327149800361564410265219<40> |