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Search: id:A123352
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| A123352 |
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Triangle read by rows, giving numbers of benzenoids (see the Cyvin-Gutman book for details). |
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+0
1
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| 1, 1, 1, 1, 2, 1, 1, 3, 5, 1, 1, 4, 14, 14, 1, 1, 5, 30, 84, 42, 1, 1, 6, 55, 330, 594, 132, 1, 1, 7, 91, 1001, 4719, 4719, 429, 1, 1, 8, 140, 2548, 26026, 81796, 40898, 1430, 1, 1, 9, 204, 5712, 111384, 884884, 1643356, 379236, 4862, 1
(list; table; graph; listen)
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OFFSET
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0,5
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COMMENT
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There is another version in A078920 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Apr 12 2007
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REFERENCES
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S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p. 183).
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FORMULA
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Triangle T(n,k)=(-1)^C(k+1,2)*Product{1<=i<=j<=k, (-2(n+1)+i+j)/(i+j)}. [From Paul Barry (pbarry(AT)wit.ie), Jan 22 2009]
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EXAMPLE
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Triangle begins:
1
1 1
1 2 1
1 3 5 1
1 4 14 14 1
1 5 30 84 42 1
1 6 55 330 594 132 1
1 7 91 1001 4719 4719 429 1
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CROSSREFS
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Diagonals give A000108, A005700, A006149, A006150, A006151, etc.
Cf. A000012, A000027, A000330, A006858, A091962.
Sequence in context: A111672 A128198 A123349 this_sequence A114163 A090234 A007754
Adjacent sequences: A123349 A123350 A123351 this_sequence A123353 A123354 A123355
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KEYWORD
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nonn,tabl
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Oct 14 2006
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EXTENSIONS
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More terms from Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Apr 12 2007
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