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A202012
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Expansion of (1-x+x^2)/((1-x)(1-x-x^2-x^3)).
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1
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1, 1, 3, 6, 11, 21, 39, 72, 133, 245, 451, 830, 1527, 2809, 5167, 9504, 17481, 32153, 59139, 108774, 200067, 367981, 676823, 1244872, 2289677, 4211373, 7745923, 14246974, 26204271, 48197169, 88648415, 163049856
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OFFSET
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0,3
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COMMENTS
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LINKS
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FORMULA
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a(n) = 2*a(n-1) - a(n-4), n>3.
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MATHEMATICA
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CoefficientList[Series[(1-x+x^2)/((1-x)(1-x-x^2-x^3)), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 0, 0, -1}, {1, 1, 3, 6}, 40] (* Harvey P. Dale, Apr 21 2014 *)
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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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