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A219205
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a(n) = 3^(n-1)*(3^n - 1), n >= 0.
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1
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0, 2, 24, 234, 2160, 19602, 176904, 1593594, 14346720, 129133602, 1162241784, 10460294154, 94143001680, 847288078002, 7625595890664, 68630372581914, 617673381935040, 5559060523508802, 50031544969859544, 450283905503576874
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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COMMENTS
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Last digit has period 4: 0, 2, 4, 4.
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LINKS
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FORMULA
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a(n) = 12*a(n-1)-27*a(n-2). G.f.: 2*x/((3*x-1)*(9*x-1)). [Colin Barker, Nov 23 2012]
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MATHEMATICA
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LinearRecurrence[{12, -27}, {0, 2}, 20] (* Hugo Pfoertner, Feb 14 2024 *)
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PROG
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(JavaScript)
for (j=0; j<20; j++) document.write((Math.pow(3, j)-1)*Math.pow(3, j-1)+", ");
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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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