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A045310
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Number of matchings in n-cube.
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3
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OFFSET
| 1,1
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COMMENTS
| a(4)=A033532(0), a(5)=A033532(1).
a(n) is also the Hosoya index of the n-hypercube graph Q_n - Eric Weisstein, Jul 11 2011
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REFERENCES
| Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
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LINKS
| Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
Per Hakan Lundow, GrafPack (Mathematica package).
Eric Weisstein's World of Mathematics, Hosoya Index
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EXAMPLE
| Comment from Max Alekseyev, Nov 16 2009: E.g. for n=2, we have
1 matching of size 0 (i.e. the empty matching)
4 matchings of size 1 (i.e. an edge)
2 matchings of size 2 (that are the perfect matchings).
So a(2) = 1 + 4 + 2 = 7, whereas A005271(2) = 2.
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CROSSREFS
| For perfect matchings see A005271.
For matching polynomials, see A192437.
Cf. A033532.
Sequence in context: A122524 A162634 A072664 * A000157 A034902 A101429
Adjacent sequences: A045307 A045308 A045309 * A045311 A045312 A045313
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KEYWORD
| nonn,hard,more
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AUTHOR
| Per Hakan Lundow (phl(AT)theophys.kth.se)
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