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 A213970 List of primitive words over the alphabet {1,3}. 2
 1, 3, 13, 31, 113, 131, 133, 311, 313, 331, 1113, 1131, 1133, 1311, 1331, 1333, 3111, 3113, 3133, 3311, 3313, 3331, 11113, 11131, 11133, 11311, 11313, 11331, 11333, 13111, 13113, 13131, 13133, 13311, 13313, 13331, 13333, 31111, 31113, 31131, 31133, 31311, 31313, 31331, 31333, 33111, 33113, 33131, 33133, 33311, 33313, 33331 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A word w is primitive if it cannot be written as u^k with k>1; otherwise it is imprimitive. The {0,1} version of this sequence is 0, 1, 01, 10, 001, 010, 011, 100, 101, 110, 0001, 0010, 0011, 0100, 0110, 0111, 1000, 1001, 1011, 1100, 1101, 1110, 00001, 00010, 00011, 00100, 00101, 00110, 00111, 01000, 01001, 01010, 01011, 01100, 01101, 01110, 01111, 10000, 10001, 10010, 10011, 10100, 10101, 10110, 10111, 11000, 11001, 11010, 11011, 11100, 11101, 11110, ..., but this cannot be included as a sequence in the OEIS since it contains nonzero "numbers" beginning with 0. REFERENCES A. de Luca and S. Varricchio, Finiteness and Regularity in Semigroups and Formal Languages, Monographs in Theoretical Computer Science, Springer-Verlag, Berlin, 1999. See p. 10. LINKS CROSSREFS Cf. A213969-A213974. Sequence in context: A146191 A058264 A242905 * A034050 A107689 A154834 Adjacent sequences:  A213967 A213968 A213969 * A213971 A213972 A213973 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Jun 30 2012 STATUS approved

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Last modified September 20 14:21 EDT 2020. Contains 337264 sequences. (Running on oeis4.)