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A077903
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Expansion of (1-x)^(-1)/(1 + x - x^2 + 2*x^3).
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0
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1, 0, 2, -3, 6, -12, 25, -48, 98, -195, 390, -780, 1561, -3120, 6242, -12483, 24966, -49932, 99865, -199728, 399458, -798915, 1597830, -3195660, 6391321, -12782640, 25565282, -51130563, 102261126, -204522252, 409044505, -818089008, 1636178018, -3272356035, 6544712070
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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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G.f.: 1/((1+x-2x^2)*(1-x+x^2));
a(n) = Sum_{k=0..n} (2*(-2)^k/3 + 1/3)*2*sin(Pi*(n-k)/3 + Pi/3)/sqrt(3);
a(n) = 2^(n+3)*cos(Pi*n)/21 + 8*sqrt(3)*cos(Pi*n/3 + Pi/6)/63 + 4*sqrt(3)*sin(Pi*n/3 + Pi/3)/63 + 2*sqrt(3)*sin(Pi*n/3)/9 + 1/3. - Paul Barry, May 19 2004
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MATHEMATICA
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CoefficientList[Series[(1-x)^(-1)/(1+x-x^2+2x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{0, 2, -3, 2}, {1, 0, 2, -3}, 40] (* Harvey P. Dale, Apr 25 2016 *)
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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