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A120846
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a(n) = 3^n + 2^n + n.
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1
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2, 6, 15, 38, 101, 280, 799, 2322, 6825, 20204, 60083, 179206, 535549, 1602528, 4799367, 14381690, 43112273, 129271252, 387682651, 1162785774, 3487832997, 10462450376, 31385253935, 94151567458, 282446313721, 847322163900
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OFFSET
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0,1
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LINKS
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FORMULA
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a(0)=2, a(1)=6, a(2)=15, a(3)=38, a(n) = 7*a(n-1)-17*a(n-2)+17*a(n-3)-6*a(n-4). [Harvey P. Dale, Oct 24 2011]
G.f.: (x^3+7*x^2-8*x+2)/((x-1)^2*(6*x^2-5*x+1)). [Harvey P. Dale, Oct 24 2011]
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MAPLE
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MATHEMATICA
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Table[3^n + 2^n + n, {n, 0, 30}] (* or *) LinearRecurrence[{7, -17, 17, -6}, {2, 6, 15, 38}, 30] (* Harvey P. Dale, Oct 24 2011 *)
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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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