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A227492 The Wiener index of the nanostar dendrimer D_n. 1
27, 2871, 39663, 326367, 2123199, 12126591, 63900927, 319163391, 1535375871, 7186396671, 32947236351, 148643831295, 662099705343, 2918722534911, 12756670414335, 55354839662079, 238734196604415, 1024200814362111, 4373869249953279 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
D_n is defined pictorially as NS2[n] in the Chen et al. reference.
a(1) and a(2) have been checked by the direct computation of the Wiener index (using Maple).
LINKS
S. Chen and J. Yang, Second-order and third-order connectivity indices of dendrimer nanostars, International Mathematical Forum, 6, No, 5, 2011, 223-228.
FORMULA
a(n) = - 513 + 2^n*(2016*n + 9468) + 4^n*(4032*n - 8928).
G.f.: 9*(3 + 280*x + 452*x^2 - 1056*x^3 - 192*x^4)/((1-x)*(1-2*x)^2*(1-4*x)^2).
MAPLE
a := proc (n) options operator, arrow: -513+2^n*(2016*n+9468)+4^n*(4032*n-8928) end proc: seq(a(n), n = 0 .. 20);
MATHEMATICA
LinearRecurrence[{13, -64, 148, -160, 64}, {27, 2871, 39663, 326367, 2123199}, 20] (* Harvey P. Dale, Dec 30 2017 *)
CROSSREFS
Cf. A227493.
Sequence in context: A017427 A050644 A048567 * A027363 A350135 A085529
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jul 17 2013
STATUS
approved

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Last modified June 15 13:08 EDT 2024. Contains 373407 sequences. (Running on oeis4.)