OFFSET
1,2
REFERENCES
A. Salomaa, Jewels of Formal Language Theory. Computer Science Press, Rockville, MD, 1981, p. 5.
LINKS
Jarosław Grytczuk, Thue type problems for graphs, points and numbers, Discrete Math., 308 (2008), 4419-4429.
MATHEMATICA
Map[FromDigits, SubstitutionSystem[{1->{1, 2}, 2->{2, 1}}, {1}, 7]] (* Paolo Xausa, Dec 24 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 26 2003
STATUS
approved