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A109008
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a(n) = gcd(n,4).
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12
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4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4, 1, 2, 1, 4
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = 1 + [2|n] + 2*[4|n] = 2 + (-1)^n + cos(n*Pi/2), where [x|y] = 1 when x divides y, 0 otherwise.
a(n) = a(n-4) for n>3.
Dirichlet g.f.: (1 + 1/2^s + 2/4^s)*zeta(s). - R. J. Mathar, Feb 28 2011
G.f.: (4+x+2*x^2+x^3)/((1-x)*(1+x)*(1+x^2)). - R. J. Mathar, Apr 04 2011
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MAPLE
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MATHEMATICA
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PROG
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(Haskell)
a109008 = gcd 4
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CROSSREFS
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KEYWORD
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nonn,easy,mult
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AUTHOR
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STATUS
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approved
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