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A130779
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a(0)=a(1)=1, a(2)=2, a(n)=0 for n >= 3.
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9
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1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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OFFSET
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0,3
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COMMENTS
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Multiplicative with a(2)=2, a(2^e)=0 if e>1, a(p^e)=0 for odd prime p if e>=1. Dirichlet g.f. 1+2^(1-s). - R. J. Mathar, Jun 28 2011
a(n-1) is the determinant of the symmetric n X n matrix M(i,j) = rad(gcd(i,j)) for 1 <= i, j <= n, where rad(n) is the largest squarefree number dividing n (A007947). - Amiram Eldar, Jul 19 2019
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REFERENCES
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J. Sándor and B. Crstici, Handbook of Number Theory II, Kluwer, 2004, p. 265.
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LINKS
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FORMULA
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G.f.: 1+x+2x^2.
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MATHEMATICA
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LinearRecurrence[{1}, {1, 1, 2, 0}, 105] (* Ray Chandler, Jul 15 2015 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,mult,easy
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AUTHOR
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STATUS
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approved
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