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A152692
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a(n) = n*3^n - n*2^n - n*1^n.
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1
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0, 0, 8, 54, 256, 1050, 3984, 14406, 50432, 172530, 580240, 1926078, 6328128, 20619690, 66732176, 214742070, 687698944, 2193154530, 6968850192, 22073006382, 69714716480, 219623377050, 690291036688, 2165100175014
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: 2*x^2*(4-21*x+36*x^2-21*x^3)/((1-x)^2*(1-3*x)^2*(1-2*x)^2). (End)
E.g.f.: x*(3*exp(3*x) - 2*exp(2*x) - exp(x)). - G. C. Greubel, Sep 02 2018
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MATHEMATICA
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CoefficientList[Series[-(2 x^2 (-4 + 21 x - 36 x^2 + 21 x^3))/(-1 + 6 x - 11 x^2 + 6 x^3)^2, {x, 0, 50}], x] (* Stefano Spezia, Sep 04 2018 *)
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PROG
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(PARI) vector(30, n, n--; n*(3^n-2^n-1)) \\ G. C. Greubel, Sep 02 2018
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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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EXTENSIONS
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STATUS
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approved
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