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A085278
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Expansion of (1+2x)^2/((1-x^2)(1-2x)).
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2
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1, 6, 17, 38, 81, 166, 337, 678, 1361, 2726, 5457, 10918, 21841, 43686, 87377, 174758, 349521, 699046, 1398097, 2796198, 5592401, 11184806, 22369617, 44739238, 89478481, 178956966, 357913937, 715827878, 1431655761, 2863311526
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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)=16*2^n/3+(-1)^n/6-9/2.
G.f.: (2*x+1)^2 / ( (x-1)*(2*x-1)*(1+x) ). - R. J. Mathar, Nov 20 2014
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MATHEMATICA
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CoefficientList[Series[(1+2x)^2/((1-x^2)(1-2x)), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 1, -2}, {1, 6, 17}, 40] (* Harvey P. Dale, Sep 19 2016 *)
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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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EXTENSIONS
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Missing parenthesis in definition corrected by Harvey P. Dale, Sep 19 2016
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STATUS
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approved
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