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Search: id:A130753
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| A130753 |
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A folded-back triangular sequence based on symmetry of CnH2*n+2 straight chain alkanes and the number of hydrogen atoms of a given symmetry type: Besides methane at 4 there are only three symmetry types: two CH3's->6: a single CH2->2, two CH2's->4. |
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+0
1
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| 4, 6, 6, 2, 6, 4, 6, 4, 2, 6, 4, 4, 6, 4, 4, 2, 6, 4, 4, 4, 6, 4, 4, 4, 2, 6, 4, 4, 4, 4, 6, 4, 4, 4, 4, 2, 6, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 2, 6, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 2, 6, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 2, 6, 4, 4, 4, 4, 4, 4, 4, 4, 6, 4, 4, 4, 4, 4, 4, 4, 4, 2, 6, 4, 4, 4, 4
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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http://en.wikipedia.org/wiki/Alkane
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FORMULA
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a(n,m) = If[n == m == 1, 4, If[n == 1 && m >1, 6, If[Mod[m, 2] == 1 && n == Floor[m/2] + 1, 2, 4]]]
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EXAMPLE
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{4},->Ch4
{6}, ->CH3CH3
{6, 2}, ->CH3CH2CH3
{6, 4}, ->CH3CH2CH2CH3
{6, 4, 2}, ->CH3CH2CH2CH2CH3
{6, 4, 4}, ->CH3CH2CH2CH2CH2CH3
{6, 4, 4, 2}, ->CH3CH2CH2CH2CH2CH2CH3
{6, 4, 4, 4}, ->CH3CH2CH2CH2CH2CH2CH2CH3
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MATHEMATICA
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f[n_, m_] = If[n == m ==1, 4, If[n == 1 && m > 1, 6, If[Mod[m, 2] == 1 && n == Floor[m/2] + 1, 2, 4]]]; Table[Table[f[n, m], {n, 1, If[m == 1, 1, If[Mod[m, 2] == 0, Floor[m/2], Floor[m/2] + 1]]}], {m, 1, 20}]; Flatten[%]
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CROSSREFS
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Sequence in context: A009465 A119858 A123060 this_sequence A021686 A019923 A019800
Adjacent sequences: A130750 A130751 A130752 this_sequence A130754 A130755 A130756
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KEYWORD
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nonn,tabf
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jul 13 2007
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