Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 271: | \[{4^{271}-1\over3}\] | 1627 × 15242475217<11> × 115417966565804897<18> × 4635260015873357770993<22> × 1453023029482044854944519555964740294049<40> × 248927757868131890277330541567820045256364273970773286542188386932989391<72> |