Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
421: | \[2^{421}-1\] | 614002928307599<15> × 8819779591697258388298117725624832271141577326602771028307143781815455970700534027206522451123308835472505327249<112> |