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A134818
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Number of hydrocarbon structures that can be drawn (excluding stereoisomers) for n carbon atoms.
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1
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1, 3, 9, 37, 146, 772, 4449, 30307, 228605, 1921464, 17652327, 176162548, 1893738334, 21806975279
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Computed over a period of several years and confirmed using the Molgen program.
Terms for n = 8,9,10 calculated using an exhaustive algorithm and Nauty. The algorithm correctly found the 7 known terms and the known acyclic hydrocarbons (up to n=10, see A002986) were extracted from the results correctly. - Vesa Linja-aho (vesa.linja-aho(AT)tkk.fi), Apr 17 2008
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LINKS
| Brendan McKay, Nauty
Molgen, Publications
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EXAMPLE
| For n = 2 there are a(2) = 3 hydrocarbon structures that can be drawn (ethane, ethene, and ethyne).
For n = 7 there are a(7) = 4449 hydrocarbon structures that can be drawn with 7 carbons.
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CROSSREFS
| A134819 gives the number of possible structures, broken down by units of unsaturation
Sequence in context: A197309 A149021 A149022 * A002751 A119856 A077365
Adjacent sequences: A134815 A134816 A134817 * A134819 A134820 A134821
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KEYWORD
| hard,nice,nonn
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AUTHOR
| David A. Consiglio, Jr. (davecons2002(AT)yahoo.com), Jan 28 2008
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EXTENSIONS
| a(8)-a(10) from Vesa Linja-aho (vesa.linja-aho(AT)tkk.fi), Apr 17 2008
a(11) from Vesa Linja-aho (vesa.linja-aho(AT)tkk.fi), Apr 24 2008
a(12) sent by David A. Consiglio, Jr. (davecons2002(AT)yahoo.com), Apr 23 2008
a(12) corrected, a(13) and a(14) added - David Consiglio, Jr. (davecons(AT)gmail.com) Nov 3 2011
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