I know of a few applications of De-Bruijn Sequences and De Bruijn Graphs in combinatorics, applied mathematics, Engineering and computer science. But I have only found one application of De Bruijn sequences in "pure mathematics", specifically in Diophantine approximations, which is the following: http://eprints.whiterose.ac.uk/126995/1/160507953v3.pdf

Do you know of any other such applications of De Bruijn sequences in "Pure Mathematics"?