binary matrices, would have entries, yielding a square array of dimension , denoted a de Bruijn torus or simply B6. This could easily be stored on a computer—if printed with pixels of side 0.1 mm, such a matrix would require an area of approximately 26×26 square metres. The object B8, containing all binary matrices and denoted , has a total of 264 ≈ 18.447×1018 entries: storing such a matrix would require 18.5 exabits, or 2.3 exabytes of storage. At the above scale, it would cover 429×429 square kilometres. The following table illustrates the super-exponential growth. See also De Bruijn sequence De Bruijn graph References External links Minimal arrays containing all sub-array combinations of symbols: De Bruijn sequences and tori Combinatorics