

A083041


Number of symmetric sumfree subsets of {1,2,...,n1} with sums taken mod n.


0



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
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OFFSET

1,2


COMMENTS

Parker vector for K_3free graphs.


REFERENCES

P. J. Cameron, Portrait of a typical sumfree set, Surveys in combinatorics 1987, London Math. Soc. Lecture Note Ser., 123, 1987, pp. 1342.


LINKS

Table of n, a(n) for n=1..31.
D. A. Gewurz and F. Merola, Sequences realized as Parker vectors of oligomorphic permutation groups, J. Integer Seq., 6 (2003), 03.1.6


EXAMPLE

a(3) = 1, as {} is the only symmetric sumfree set ({1} is not symmetric, while {1,2} is not sumfree). a(4)=3; its symmetric sumfree subsets are {}, {1,3}, {2}.


CROSSREFS

Cf. A007865
Sequence in context: A027157 A112194 A238788 * A318611 A130067 A282906
Adjacent sequences: A083038 A083039 A083040 * A083042 A083043 A083044


KEYWORD

nonn


AUTHOR

Daniele A. Gewurz (gewurz(AT)mat.uniroma1.it), Francesca Merola (merola(AT)mat.uniroma1.it), May 06 2003


STATUS

approved



