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A006925
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Number of connected trivalent graphs with 2n nodes and girth exactly 5.
(Formerly M1879)
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14
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1, 2, 8, 48, 450, 5751, 90553, 1612905, 31297357, 652159389, 14499780660, 342646718608
(list; graph; refs; listen; history; internal format)
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OFFSET
| 5,2
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REFERENCES
| CRC Handbook of Combinatorial Designs, 1996, p. 647.
Gordon Royle, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| Jason Kimberley, Index of sequences counting connected k-regular simple graphs with girth exactly g
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FORMULA
| a(n) = A014372(n) - A014374(n).
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CROSSREFS
| Connected k-regular simple graphs with girth exactly 5: this sequence (k=3), A184945 (k=4), A184955 (k=5).
Connected 3-regular simple graphs with girth exactly g: A198303 (triangle); specified g: A006923 (g=3), A006924 (g=4), this sequence
(g=5), A006926 (g=6), A006927 (g=7).
Connected 3-regular simple graphs with girth at least g: A002851 (g=3), A014371 (g=4), A014372 (g=5), A014374 (g=6), A014375 (g=7), A014376 (g=8).
Sequence in context: A177386 A112541 A052667 * A005867 A192411 A179563
Adjacent sequences: A006922 A006923 A006924 * A006926 A006927 A006928
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KEYWORD
| nonn,hard,more
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Definition corrected to include "connected", and "girth at least 5" minus "girth at least 6" formula provided by Jason Kimberley, Dec 12 2009
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