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Search: id:A083041
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| A083041 |
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Number of symmetric sum-free subsets of {1,2,...,n-1} with sums taken mod n. |
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+0
1
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| 1, 2, 1, 3, 3, 4, 4, 8, 4, 14, 11, 14, 16, 31, 19, 45, 37, 56, 55, 106, 55, 164, 122, 179, 190, 353, 178, 467, 379, 648, 541
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Parker vector for K_3-free graphs.
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REFERENCES
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P. J. Cameron, Portrait of a typical sum-free set, Surveys in combinatorics 1987, London Math. Soc. Lecture Note Ser., 123, 1987, pp. 13-42.
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LINKS
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D. A. Gewurz and F. Merola, Sequences realized as Parker vectors of oligomorphic permutation groups, J. Integer Seq., 6 (2003), 03.1.6
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EXAMPLE
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a(3) = 1, as {} is the only symmetric sum-free set ({1} is not symmetric, while {1,2} is not sum-free). a(4)=3; its symmetric sum-free subsets are {}, {1,3}, {2}.
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CROSSREFS
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Cf. A007865
Adjacent sequences: A083038 A083039 A083040 this_sequence A083042 A083043 A083044
Sequence in context: A029137 A027157 A112194 this_sequence A130067 A032303 A032215
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KEYWORD
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nonn
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AUTHOR
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Daniele A. Gewurz (gewurz(AT)mat.uniroma1.it), Francesca Merola (merola(AT)mat.uniroma1.it), May 06 2003
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