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 A161826 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
 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; text; internal format)
 OFFSET 1,3 COMMENTS A subset S of V is vertex-independent if there is no edge (X,Y,Z) with X, Y, Z all in S. LINKS FORMULA a(2k)=1, a(2k+1)=4 for k >= 5. 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: A286157 A016460 A248645 * A097887 A019761 A188614 Adjacent sequences:  A161823 A161824 A161825 * A161827 A161828 A161829 KEYWORD nonn AUTHOR N. J. A. Sloane, Feb 10 2010 STATUS approved

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Last modified April 10 10:39 EDT 2021. Contains 342845 sequences. (Running on oeis4.)