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A099450
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Expansion of 1/(1 - 5x + 7x^2).
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4
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1, 5, 18, 55, 149, 360, 757, 1265, 1026, -3725, -25807, -102960, -334151, -950035, -2411118, -5405345, -10148899, -12907080, 6506893, 122884025, 568871874, 1984171195, 5938752857, 15804565920, 37451559601, 76625836565, 120968265618, 68460472135, -504475498651
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OFFSET
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0,2
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COMMENTS
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Associated to the knot 7_7 by the modified Chebyshev transform A(x)-> (1/(1+x^2)^2)A(x/(1+x^2)). See A099451 and A099452.
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LINKS
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FORMULA
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a(n) = sum{k=0..floor(n/2), binomial(n-k, k)(-7)^k*5^(n-2k)}.
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MATHEMATICA
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CoefficientList[Series[1/(1-5x+7x^2), {x, 0, 40}], x] (* or *) LinearRecurrence[ {5, -7}, {1, 5}, 40] (* Harvey P. Dale, Oct 21 2016 *)
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PROG
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(Sage) [lucas_number1(n, 5, 7) for n in range(1, 30)] # Zerinvary Lajos, Apr 22 2009
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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STATUS
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approved
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