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A111575
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Powers of 3 repeated four times.
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7
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1, 1, 1, 1, 3, 3, 3, 3, 9, 9, 9, 9, 27, 27, 27, 27, 81, 81, 81, 81, 243, 243, 243, 243, 729, 729, 729, 729, 2187, 2187, 2187, 2187, 6561, 6561, 6561, 6561, 19683, 19683, 19683, 19683, 59049, 59049, 59049, 59049, 177147, 177147, 177147, 177147, 531441
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,5
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COMMENTS
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Generating sequence for the number of 0's and 1's (run lengths) in the parity of A006072, A111065 and A118594.
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LINKS
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FORMULA
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a(n) = 3^floor(n/4).
O.g.f.: -(1+x)*(1+x^2)/(-1+3*x^4). - R. J. Mathar, Jan 08 2008
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EXAMPLE
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a(10) = 3^floor(10/4) = 3^2 = 9.
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MATHEMATICA
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With[{pt=3^Range[0, 15]}, Sort[Join[pt, pt, pt, pt]]] (* Harvey P. Dale, Sep 17 2011 *)
Table[PadRight[{}, 4, 3^n], {n, 0, 15}]//Flatten (* Harvey P. Dale, Jan 17 2019 *)
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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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STATUS
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approved
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