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Search: id:A066297
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| A066297 |
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Number of ternary square-free loops. |
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+0
1
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| 1, 3, 6, 6, 12, 0, 18, 0, 24, 0, 0, 66, 72, 78, 0, 30, 48, 0, 252, 228, 300, 42, 462, 690, 720, 750, 702, 810, 1260, 2088, 3870
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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A square is an adjacent pair of repeats, e.g. "aa" or "abcabc". A loop is a word that may be rotated before being tested (for squares).
Several similar sequences (with same zeros) can be constructed from equivalence classes of the loops.
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EXAMPLE
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a(1)=3, size of {"a","b","c"); a(6)=18, size of {"abacbc","bacbca",...,"cbabca"}
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CROSSREFS
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Variant of A006156. See also A001037, A006206.
Adjacent sequences: A066294 A066295 A066296 this_sequence A066298 A066299 A066300
Sequence in context: A119980 A066779 A132384 this_sequence A012212 A080866 A066393
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KEYWORD
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hard,nice,nonn
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AUTHOR
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Paul Parsons (paul.parsons6(AT)btinternet.com)
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EXTENSIONS
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Higher terms: a(n)>0 for 30<n<=56; no zeros known after a(17).
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