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A114196
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Expansion of (1-3x)/(1-6x+8x^2+x^3).
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1
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1, 3, 10, 35, 127, 472, 1781, 6783, 25978, 99823, 384331, 1481424, 5714073, 22048715, 85098282, 328485899, 1268080423, 4895497064, 18899853101, 72967061671, 281708048154, 1087611942455, 4199040207827, 16211637659168
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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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a(n)=6a(n-1)-8a(n-2)-a(n-3); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(n-k, j)C(j+k, 2k)2^(j-k)}}.
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MATHEMATICA
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CoefficientList[Series[(1-3x)/(1-6x+8x^2+x^3), {x, 0, 30}], x] (* or *) LinearRecurrence[{6, -8, -1}, {1, 3, 10}, 30] (* Harvey P. Dale, Feb 02 2012 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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