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A154383
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Powers of 4 at even indices, two times powers of 4 at odd indices.
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3
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1, 0, 4, 2, 16, 8, 64, 32, 256, 128, 1024, 512, 4096, 2048, 16384, 8192, 65536, 32768, 262144, 131072, 1048576, 524288, 4194304, 2097152, 16777216, 8388608, 67108864, 33554432, 268435456, 134217728, 1073741824, 536870912, 4294967296, 2147483648, 17179869184, 8589934592, 68719476736, 34359738368, 274877906944
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = 4*a(n-2), n>3.
a(2n+1) = a(2n)/2, n>0.
G.f.: (1 + 2*x^3)/((1-2*x)*(2*x+1)). - R. J. Mathar, May 21 2009
a(n) = (5 + 3*(-1)^n)*2^(n-3), n>1. - R. J. Mathar, May 21 2009
E.g.f.: (1/4)*(-2*x + sinh(2*x) + 4*cosh(2*x)). - G. C. Greubel, Sep 15 2016
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MATHEMATICA
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Join[{1, 0}, Table[(5 + 3*(-1)^n)*2^(n - 3), {n, 2, 20}]] (* G. C. Greubel, Sep 15 2016 *)
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PROG
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(Magma) [1, 0] cat [(5+3*(-1)^n)*2^(n-3): n in [2..40]]; // Vincenzo Librandi, Sep 16 2016
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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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