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A323446
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Number of binary strings w of length n that cannot be written in the form xyz, with x,z both nonempty and xz a square.
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0
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2, 2, 4, 6, 8, 12, 16, 26, 36, 70, 104, 220, 372, 758, 1408, 2874, 5472, 11056, 21696, 43546, 86060, 172514, 343068, 686888, 1369484, 2740080, 5471464, 10945900, 21872228, 43749868, 87460604, 174645564, 348957458
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OFFSET
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1,1
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COMMENTS
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A square is a nonempty block of the form XX.
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LINKS
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Table of n, a(n) for n=1..33.
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EXAMPLE
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For n = 6 the 12 solutions are {000001, 000011, 000111, 001011, 001111, 011111} and their complements.
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CROSSREFS
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Sequence in context: A080054 A108494 A078578 * A018129 A091915 A123862
Adjacent sequences: A323443 A323444 A323445 * A323447 A323448 A323449
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KEYWORD
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nonn,more
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AUTHOR
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Jeffrey Shallit, Jan 15 2019
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EXTENSIONS
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a(21)-a(33) from Lars Blomberg, Jan 26 2019
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STATUS
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approved
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