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Search: id:A033301
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| A033301 |
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Number of 4-valent (or quartic) graphs with n nodes. |
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+0
11
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| 1, 1, 2, 6, 16, 60, 266, 1547, 10786, 88193, 805579, 8037796, 86223660, 985883873, 11946592242
(list; graph; listen)
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OFFSET
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5,3
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COMMENT
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Because the triangle A051031 is symmetric, a(n) is also the number of (n-5)-regular graphs on n vertices. [From Jason Kimberley (Jason.Kimberley(AT)newcastle.edu.au), Sep 22 2009]
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REFERENCES
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R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
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LINKS
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M. Meringer, Tables of Regular Graphs
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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Euler transform of A006820 with a(1)=a(2)=a(3)=a(4)=0 - Martin Fuller (martin_n_fuller(AT)btinternet.com), Dec 04 2006
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CROSSREFS
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Cf. A006820, A033483.
Regular graphs A005176 (any degree), A051031 (triangular array), chosen degrees: A000012 (k=0), A059841 (k=1), A008483 (k=2), A005638 (k=3), A033301 (k=4), A165626 (k=5), A165627 (k=6), A165628 (k=7). [From Jason Kimberley (Jason.Kimberley(AT)newcastle.edu.au), Nov 07 2009]
Sequence in context: A006820 A131385 A027742 this_sequence A093113 A150030 A150031
Adjacent sequences: A033298 A033299 A033300 this_sequence A033302 A033303 A033304
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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R. C. Read (rcread(AT)math.uwaterloo.ca)
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EXTENSIONS
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More terms from Axel Kohnert (kohnert(AT)uni-bayreuth.de), Jul 24 2003
The Euler transform of A006820 gives a(17),a(18),a(19). - Jason Kimberley (Jason.Kimberley(AT)newcastle.edu.au), Sep 12 2009
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