Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 278: | \[2^{278}-1\] | 3 × 4506937 × 5625767248687<13> × 123876132205208335762278423601<30> × 51542639524661795300074174250365699<35> |