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A026843
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a(n) = T(2n,n+3), T given by A026725.
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2
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1, 8, 46, 233, 1108, 5083, 22805, 100827, 441311, 1917751, 8289965, 35694218, 153225617, 656213596, 2805143526, 11973556060, 51047361676, 217420991444, 925300665762, 3935293406942, 16727533586006, 71069911887898, 301835332909216
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OFFSET
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3,2
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COMMENTS
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LINKS
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FORMULA
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a(n) ~ phi^(3*n-4) / sqrt(5), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Jul 19 2019
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MATHEMATICA
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Drop[CoefficientList[Series[(1-Sqrt[1-4*x])^7/(16*x^2*(8*x^2 -(1-Sqrt[1-4*x])^3)), {x, 0, 40}], x], 3] (* G. C. Greubel, Jul 19 2019 *)
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PROG
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(PARI) my(x='x+O('x^40)); Vec( (1-sqrt(1-4*x))^7/(16*x^2*(8*x^2 -(1-sqrt(1-4*x))^3)) ) \\ G. C. Greubel, Jul 19 2019
(Magma) R<x>:=PowerSeriesRing(Rationals(), 40); Coefficients(R!( (1-Sqrt(1-4*x))^7/(16*x^2*(8*x^2 -(1-Sqrt(1-4*x))^3)) )); // G. C. Greubel, Jul 19 2019
(Sage) a=((1-sqrt(1-4*x))^7/(16*x^2*(8*x^2 -(1-sqrt(1-4*x))^3)) ).series(x, 45).coefficients(x, sparse=False); a[3:40] # G. C. Greubel, Jul 19 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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