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Search: id:A000639
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| A000639 |
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Alkyl benzenes with n carbon atoms: C(n)H(2n-6).
(Formerly M3341 N1344)
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+0
1
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| 0, 0, 0, 0, 0, 1, 1, 4, 8, 22, 51, 136, 335, 871, 2217, 5749, 14837, 38636, 100622, 263381, 690709, 1817544, 4793449, 12675741, 33592349, 89223734, 237455566, 633176939, 1691377956, 4525792533, 12129365576, 32556355947, 87508275471, 235529797422
(list; graph; listen)
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OFFSET
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1,8
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REFERENCES
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N. L. Biggs et al., Graph Theory 1736-1936, Oxford, 1976, p. 71.
G. Polya, Algebraische Berechnung der Anzahl der Isomeren einiger organischer Verbindungen, Zeit. f. Kristall., 93 (1936), 415-443 (p. 422).
R. C. Read, The Enumeration of Acyclic Chemical Compounds, pp. 25-61 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976; see p. p. 22, Eq. (H).
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EXAMPLE
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a(8)=4 because the unique isomers are 1,2-Dimethylbenzene; 1,3-Dimethylbenzene; 1,4-Dimethylbenzene, 1-Ethylbenzene. All have formula C(8)H(10)
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CROSSREFS
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G.f.: = (1/12)*(B(x)^6+4*B(x^2)^3+2*B(x^3)^2+3*B(x)^2*B(x^2)^2+2*B(x^6)), where B = g.f. of A000598.
Cf. A000598 (Alkyl radicals).
Sequence in context: A050482 A003606 A048657 this_sequence A052528 A058855 A057583
Adjacent sequences: A000636 A000637 A000638 this_sequence A000640 A000641 A000642
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KEYWORD
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nonn,easy,nice
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AUTHOR
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njas
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EXTENSIONS
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Better description from Bruce Corrigan (scentman(AT)myfamily.com), Oct 23 2002
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