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A005176
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Number of regular graphs with n nodes.
(Formerly M0303)
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20
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1, 1, 2, 2, 4, 3, 8, 6, 22, 26, 176, 546, 19002, 389454, 50314870, 2942198546, 1698517037030
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
P. Steinbach, Field Guide to Simple Graphs. Design Lab, Albuquerque NM, 1990.
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LINKS
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Table of n, a(n) for n=0..16.
E. Friedman, Illustration of small graphs
Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g
Eric Weisstein's World of Mathematics, Regular Graph.
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FORMULA
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a(n) = A005177(n) + A068932(n). - David Wasserman, Mar 08 2002
Row sums of triangle A051031.
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CROSSREFS
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Not necessarily connected simple regular graphs: A005176 (any degree), A051031 (triangular array), specified degree k: A000012 (k=0), A059841 (k=1), A008483 (k=2), A005638 (k=3), A033301 (k=4), A165626 (k=5), A165627 (k=6), A165628 (k=7).
Simple regular graphs of any degree: A005177 (connected), A068932 (disconnected), this sequence (not necessarily connected).
Not necessarily connected regular simple graphs with girth at least g: this sequence (g=3), A185314 (g=4), A185315 (g=5), A185316 (g=6), A185317 (g=7), A185318 (g=8), A185319 (g=9).
Sequence in context: A056429 A133806 A185333 * A050335 A223537 A140860
Adjacent sequences: A005173 A005174 A005175 * A005177 A005178 A005179
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from David Wasserman, Mar 08 2002
Terms a(15) and a(16) were appended by Jason Kimberley, Sep 25 2009
Edited by Jason Kimberley, Jan 06 2011 and May 24 2012
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STATUS
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approved
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