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A161826
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Number of maximal vertex-independent sets in the hypergraph with nodes V = {1, 2, ..., n} and "edges" consisting of the triples (X,Y,Z) with X<Y<Z and X+Y=Z.
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3
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1, 1, 3, 2, 6, 1, 6, 1, 5, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4, 1, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| A subset S of V is vertex-independent if there is no edge (X,Y,Z) with X, Y, Z all in S.
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FORMULA
| a(2k)=1, a(2k+1)=4 for k >= 5.
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CROSSREFS
| J. Sedlacek, On a set system, Annals New York Acad. Sci., 175 (No. 1, 1970), 329-330.
Cf. A002848, A002849, A108235.
Sequence in context: A005266 A005267 A016460 * A097887 A019761 A188614
Adjacent sequences: A161823 A161824 A161825 * A161827 A161828 A161829
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Feb 10 2010
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