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A227707
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The terminal Wiener index of the dendrimer D_n defined pictorially in Fig. 1 of the Heydari et al. reference.
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3
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12, 78, 444, 2328, 11568, 55392, 258240, 1180032, 5309184, 23594496, 103812096, 452990976, 1962946560, 8455741440, 36238835712, 154618920960, 657130192896, 2783139201024, 11751031308288, 49478024822784, 207807700795392, 870813215490048, 3641582523777024, 15199648767541248
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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REFERENCES
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A. Heydari, I. Gutman, On the terminal index of thorn graphs, Kragujevac J. Sci., 32, 2010, 57-64.
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LINKS
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FORMULA
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a(n) = 3*2^n + 9*4^n*(n+1).
G.f.: 6*(2-7*x+8*x^2)/((1-2*x)*(1-4*x)^2).
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MAPLE
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a := proc (n) options operator, arrow: 3*2^n+9*4^n*(n+1) end proc: seq(a(n), n = 0 .. 25);
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MATHEMATICA
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CoefficientList[Series[6 (2 - 7 x + 8 x^2) / ((1 - 2 x) (1 - 4 x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Aug 04 2013 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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