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Search: id:A108667
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| A108667 |
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Triangle read by rows: T(n,k)=9kn+14(n+k)+20 (0<=k<=n). |
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+0
1
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| 20, 34, 57, 48, 80, 112, 62, 103, 144, 185, 76, 126, 176, 226, 276, 90, 149, 208, 267, 326, 385, 104, 172, 240, 308, 376, 444, 512, 118, 195, 272, 349, 426, 503, 580, 657, 132, 218, 304, 390, 476, 562, 648, 734, 820, 146, 241, 336, 431, 526, 621, 716, 811
(list; table; graph; listen)
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OFFSET
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0,1
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COMMENT
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Kekule numbers for certain benzenoids. T(n,n)=9n^2+28n+20 =A051872(n+2)
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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 (p.102).
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FORMULA
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G.f.=(20-6z-3tz+t^2*z^2-16tz^2-4t^2*z^3)/[(1-z)^2*(1-tz)^3]
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EXAMPLE
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Triangle begins:
20;
34,57;
48,80,112;
62,103,144,185;
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MAPLE
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T:=proc(n, k) if k<=n then 9*k*n+14*(n+k)+20 else 0 fi end: for n from 0 to 10 do seq(T(n, k), k=0..n) od; # yields sequence in triangular form
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CROSSREFS
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Cf. A051872.
Sequence in context: A165236 A067468 A127906 this_sequence A108669 A039343 A043166
Adjacent sequences: A108664 A108665 A108666 this_sequence A108668 A108669 A108670
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KEYWORD
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nonn,tabl
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 14 2005
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