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A302507
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a(n) = 4*(3^n-1).
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0
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0, 8, 32, 104, 320, 968, 2912, 8744, 26240, 78728, 236192, 708584, 2125760, 6377288, 19131872, 57395624, 172186880, 516560648, 1549681952, 4649045864, 13947137600, 41841412808, 125524238432, 376572715304, 1129718145920, 3389154437768, 10167463313312
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OFFSET
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0,2
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COMMENTS
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Triameter of the n-Sierpinski carpet graph.
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LINKS
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FORMULA
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a(n) = 4*a(n-1) - 3*a(n-2).
G.f.: 8*x/((1 - x)*(1 - 3*x)).
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MATHEMATICA
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Table[4 (3^n - 1), {n, 0, 20}]
4 (3^Range[0, 20] - 1)
LinearRecurrence[{4, -3}, {8, 32}, {0, 20}]
CoefficientList[Series[8 x/((1 - x) (1 - 3 x)), {x, 0, 20}], x]
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PROG
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(PARI) for(n=0, 30, print1(4*(3^n-1), ", ")) \\ G. C. Greubel, Apr 09 2018
(Magma) [4*(3^n -1): n in [0..30]]; // G. C. Greubel, Apr 09 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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