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A216271
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Expansion of (1-x)/((1-2x)(1-4x+x^2)).
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1
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1, 5, 21, 83, 319, 1209, 4549, 17051, 63783, 238337, 890077, 3322995, 12403951, 46296905, 172791861, 644886923, 2406788599, 8982333009, 33522674509, 125108627171, 466912358463, 1742541855257, 6503257159717, 24270490977915, 90578715140551, 338044386361505, 1261598863859901
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: (1-x)/(1-6x+9x^2-2x^3).
a(n) = 6*a(n-1) - 9*a(n-2) + 2*a(n-3), a(0) = 1, a(1) = 5, a(2) = 21.
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MATHEMATICA
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CoefficientList[Series[(1-x)/((1-2x)(1-4x+x^2)), {x, 0, 30}], x] (* Harvey P. Dale, Oct 05 2019 *)
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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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