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Search: id:A003055
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| A003055 |
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Number of connected graphs, up to homeomorphism, that can be drawn in the plane using unit-length edges.
(Formerly M2464)
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+0
2
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OFFSET
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1,3
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COMMENT
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K_4 can't be so drawn even though it is planar. Although a square with a tail of length 1 and a triangle with a tail of length 2 are nonisomorphic graphs with five edges, they are homeomorphic as topological spaces.
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REFERENCES
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M. Gardner, The Unexpected Hanging and Other Mathematical Diversions. Simon and Schuster, NY, 1969, p. 80.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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CROSSREFS
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Cf. A066951.
Adjacent sequences: A003052 A003053 A003054 this_sequence A003056 A003057 A003058
Sequence in context: A133999 A014610 A117591 this_sequence A018101 A068013 A018104
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KEYWORD
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nonn,more,nice
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AUTHOR
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njas
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EXTENSIONS
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Corrected by Brendan McKay (bdm(AT)cs.anu.edu.au) and Les Reid (les(AT)math.smsu.edu), May 25, 2002
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