Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
655: | \[2^{655}-1\] | 31 × 263 × 597361 × 2576754528566814601<19> × 351182936972570824983481<24> × 10350794431055162386718619237468234569<38> × 15333541100090824437129533485272856744656791<44> × 213732345927036277063342078342573605826938066316475164889831797001<66> |