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A087432
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Expansion of 1+x*(1-x-4*x^2)/((1+x)*(1-2*x)*(1-3*x)).
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3
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1, 1, 3, 7, 19, 51, 143, 407, 1179, 3451, 10183, 30207, 89939, 268451, 802623, 2402407, 7196299, 21567051, 64657463, 193885007, 581480259, 1744091251, 5231574703, 15693326007, 47077181819, 141225953051, 423666674343
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OFFSET
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0,3
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COMMENTS
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Binomial transform of A047849 (with interpolated zeros, 1,0,2,0,6,0,...). Binomial transform is A087433.
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LINKS
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FORMULA
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a(n) = (-1)^n/6+2^n/3+3^n/6, n>0.
For n>4, a(n) = 6*a(n-1) - 9*a(n-2) - 4*a(n-3) + 12*a(n-4). - Gary W. Adamson, Jun 14 2006
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MATHEMATICA
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CoefficientList[Series[1+x (1-x-4x^2)/((1+x)(1-2x)(1-3x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{4, -1, -6}, {1, 1, 3, 7}, 30] (* Harvey P. Dale, Aug 23 2017 *)
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PROG
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(PARI) Vec((x-1)*(2*x^2+2*x-1)/((1+x)*(1-2*x)*(1-3*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012, corrected Nov 27 2014
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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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STATUS
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approved
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