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A130979
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G.f.: 7/(3 + 4*sqrt(1-28*x)).
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6
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1, 8, 120, 2192, 44248, 949488, 21237168, 489517344, 11544312984, 277190766896, 6753051796240, 166505875155936, 4146984734796016, 104174408364697952, 2636346768784492128, 67149645964991840832, 1720072455615130558488
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OFFSET
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0,2
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COMMENTS
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Number of walks of length 2n on the 8-regular tree beginning and ending at some fixed vertex. Hankel transform is A135315. - Philippe Deléham, Feb 25 2009
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LINKS
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FORMULA
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D-finite with recurrence: n*a(n) +2*(-46*n+21)*a(n-1) +896*(2*n-3)*a(n-2)=0. - R. J. Mathar, Jan 20 2020
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MATHEMATICA
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CoefficientList[Series[7/(3 + 4*Sqrt[1 - 28*x]), {x, 0, 50}], x] (* G. C. Greubel, Jan 28 2017 *)
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PROG
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(PARI) Vec(7/(3 + 4*sqrt(1-28*x)) + O(x^50)) \\ G. C. Greubel, Jan 28 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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