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A128986
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a(n) = (n^3 - n^2)*3^n.
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1
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0, 36, 486, 3888, 24300, 131220, 642978, 2939328, 12754584, 53144100, 214347870, 841802544, 3233287044, 12187005012, 45199057050, 165299408640, 597144113712, 2133912053412, 7552375012566, 26499561447600, 92260315250460
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = 12*a(n-1) - 54*a(n-2) + 108*a(n-3) - 81*a(n-4). - Vincenzo Librandi, Feb 11 2013
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MATHEMATICA
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LinearRecurrence[{12, -54, 108, -81}, {0, 36, 486, 3888}, 30] (* Vincenzo Librandi, Feb 11 2013 *)
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PROG
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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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