You’re thinking of De Brujin sequences, not superpermutations, unless there’s an additional restriction that a digit cannot be used twice in a password.
Yes, and in this case the sequence is specifically the "classic" De Bruijn sequence [1]; however, there are other sequences that bear De Bruin's name, such as the Moser de Bruijn sequence, which is the one I reference most due to its relation to Z-order curves and pairing functions.
