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A163941
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Fourth right hand column of triangle A163940.
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4
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1, 9, 52, 246, 1039, 4083, 15274, 55152, 193957, 668397, 2266816, 7589418, 25143355, 82571751, 269173078, 871958244, 2809322833, 9008574945, 28768068460, 91532284830, 290283189991, 917912770779, 2894936303362
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: 1/((1-x)*(1-2*x)*(1-3*x)^2).
a(n) = (1/4)*(2^(n+5) + (2*n - 3)*3^(n+2) - 1).
a(n) = 9*a(n-1) - 29*a(n-2) + 39*a(n-3) - 18*a(n-4).
E.g.f.: (1/4)*(32*exp(2*x) + 27*(2*x-1)*exp(3*x) - exp(x)). - G. C. Greubel, Aug 13 2017
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MATHEMATICA
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LinearRecurrence[{9, -29, 39, -18}, {1, 9, 52, 246}, 30] (* or *) CoefficientList[ Series[1/((1-x)(1-2x)(1-3x)^2), {x, 0, 30}], x] (* Harvey P. Dale, Aug 14 2011 *)
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PROG
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(PARI) Vec(1/((1-x)*(1-2*x)*(1-3*x)^2) + O(x^30)) \\ Michel Marcus, Feb 12 2015
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CROSSREFS
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Equals the fourth right hand column of A163940.
A163942 is another right hand column.
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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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