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A138231
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A009545 alternated with its first differences.
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2
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0, 1, 1, 1, 2, 0, 2, -2, 0, -4, -4, -4, -8, 0, -8, 8, 0, 16, 16, 16, 32, 0, 32, -32, 0, -64, -64, -64, -128, 0, -128, 128, 0, 256, 256, 256, 512, 0, 512, -512, 0, -1024, -1024, -1024, -2048, 0, -2048, 2048, 0, 4096, 4096, 4096, 8192, 0, 8192, -8192, 0, -16384, -16384
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OFFSET
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0,5
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COMMENTS
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The unsigned sequence contains 3 copies of the strictly positive powers of 2.
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LINKS
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FORMULA
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a(n) = 2a(n-2)-2a(n-4). a(n) = -4a(n-8), n > 7.
O.g.f.: x(1+x-x^2)/(1-2x^2+2x^4). - R. J. Mathar, Jul 08 2008
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MATHEMATICA
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With[{c=LinearRecurrence[{2, -2}, {0, 1}, 40]}, Riffle[c, Differences[c]]] (* or *) LinearRecurrence[{0, 2, 0, -2}, {0, 1, 1, 1}, 80] (* Harvey P. Dale, Oct 15 2017 *)
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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