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 A309013 Lexicographically earliest squarefree sequence of nonnegative integers whose even and odd bisections are also squarefree. 1
 0, 1, 2, 0, 1, 3, 0, 1, 2, 0, 3, 1, 0, 2, 1, 0, 3, 1, 0, 4, 2, 0, 1, 2, 0, 3, 1, 0, 2, 1, 0, 3, 1, 0, 4, 3, 0, 1, 2, 0, 1, 3, 0, 2, 1, 0, 2, 3, 0, 1, 2, 0, 1, 3, 0, 4, 1, 0, 3, 1, 0, 2, 1, 0, 4, 1, 0, 3, 1, 0, 2, 3, 0, 1, 2, 0, 1, 3, 0, 2, 1, 0, 2, 3, 0, 1, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A sequence is squarefree if it has no subsequence of the form XX. Is this sequence unbounded? LINKS Rémy Sigrist, C program for A309013 FORMULA Apparently, a(3*k+1) = 0 for any k >= 0. EXAMPLE For n = 1: - "0" is squarefree, - hence a(1) = 0. For n = 2: - "00" is not squarefree, - "01" and "1" are squarefree, - hence a(2) = 1. For n = 3: - "010" is squarefree but "00" is not, - "011" is not squarefree, - "012" and "02" are squarefree, - hence a(3) = 2. For n = 4: - "0120" and "10" are squarefree, - hence a(4) = 0. PROG (C) See Links section. CROSSREFS Cf. A007814, A309011. Sequence in context: A225682 A144185 A143987 * A112760 A096087 A128138 Adjacent sequences:  A309010 A309011 A309012 * A309014 A309015 A309016 KEYWORD nonn AUTHOR Rémy Sigrist, Jul 06 2019 STATUS approved

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Last modified January 27 16:20 EST 2022. Contains 350608 sequences. (Running on oeis4.)