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A054923
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Triangle read by rows: number of connected graphs with k >= 0 edges and n nodes (1<=n<=k+1).
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5
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1, 0, 1, 0, 0, 1, 0, 0, 1, 2, 0, 0, 0, 2, 3, 0, 0, 0, 1, 5, 6, 0, 0, 0, 1, 5, 13, 11, 0, 0, 0, 0, 4, 19, 33, 23, 0, 0, 0, 0, 2, 22, 67, 89, 47, 0, 0, 0, 0, 1, 20, 107, 236, 240, 106, 0, 0, 0, 0, 1, 14, 132, 486, 797, 657, 235, 0, 0, 0, 0, 0, 9, 138, 814, 2075, 2678, 1806, 551, 0, 0, 0, 0, 0, 2, 95, 1454, 8404, 22950, 33851, 28908
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,10
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COMMENTS
| The diagonal n = k+1 is A000055(n). [From Jonathan Vos Post (jvospost3(AT)gmail.com), Aug 10 2008]
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REFERENCES
| G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.
F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 93, Table 4.2.2; p. 241, Table A2.
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LINKS
| Gordon Royle, Small graphs
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EXAMPLE
| 1; 0 1; 0 0 1; 0 0 1 2; 0 0 0 2 3; 0 0 0 1 5 6; ... (so with 5 edges there's 1 graph with 4 nodes, 5 with 5 nodes and 6 with 6 nodes). [Typo corrected by Anders Haglund, Jul 08 2008]
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CROSSREFS
| Cf. A002905, A008406, A046751, A054924, A046742.
Sequence in context: A071548 A143063 A175070 * A057108 A063958 A126164
Adjacent sequences: A054920 A054921 A054922 * A054924 A054925 A054926
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KEYWORD
| nonn,easy,nice,tabl
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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