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Search: id:A002905
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| A002905 |
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Number of connected graphs with n edges.
(Formerly M2486 N0985)
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+0
10
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| 1, 1, 1, 3, 5, 12, 30, 79, 227, 710, 2322, 8071, 29503, 112822, 450141, 1867871, 8037472, 35787667, 164551477, 779945969, 3804967442, 19079312775, 98211456209, 518397621443, 2802993986619
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.
M. L. Stein and P. R. Stein, Enumeration of Linear Graphs and Connected Linear Graphs up to $p = 18$ Points. Report LA-3775, Los Alamos Scientific Laboratory of the University of California, Los Alamos, NM, Oct 1967.
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LINKS
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P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
Gordon Royle, Small graphs
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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a(3) = 3 since the three connected graphs with three edges are a path, a triangle and a "Y".
The first difference between this sequence and A046091 is for n=9 edges where we see K_{3,3}, the well-known "utility graph".
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CROSSREFS
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Column sums of A054924 or equivalently row sums of A054923.
Cf. A000664, A046091 (for connected planar graphs).
Apart from a(3), same as A003089.
Adjacent sequences: A002902 A002903 A002904 this_sequence A002906 A002907 A002908
Sequence in context: A056690 A066951 A046091 this_sequence A087610 A099791 A028268
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KEYWORD
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nonn,nice
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AUTHOR
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njas
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 12 2000
More terms from Gordon Royle (gordon(AT)csse.uwa.edu.au), Jun 05 2003
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