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A304509
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a(n) = 63*2^n - 39 (n>=1).
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4
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87, 213, 465, 969, 1977, 3993, 8025, 16089, 32217, 64473, 128985, 258009, 516057, 1032153, 2064345, 4128729, 8257497, 16515033, 33030105, 66060249, 132120537, 264241113, 528482265, 1056964569, 2113929177, 4227858393, 8455716825, 16911433689, 33822867417, 67645734873
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OFFSET
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1,1
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COMMENTS
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a(n) = number of vertices of the dendrimer nanostar NS2[n], defined pictorially in Fig. 2 of the Madanshekaf reference.
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REFERENCES
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A. Madanshekaf, The Randic index of some dendrimer nanostars, J. Appl. Math. & Informatics, 29, No. 5-6, 2011, 1075-1080.
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LINKS
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FORMULA
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G.f.: 3*x*(29 - 16*x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>2.
(End)
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MAPLE
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seq(63*2^n-39, n = 1 .. 40);
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MATHEMATICA
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PROG
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(PARI) Vec(3*x*(29 - 16*x) / ((1 - x)*(1 - 2*x)) + O(x^40)) \\ Colin Barker, May 15 2018
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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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