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A346482
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Dirichlet inverse of A005171, the characteristic function of nonprimes.
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4
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1, 0, 0, -1, 0, -1, 0, -1, -1, -1, 0, -1, 0, -1, -1, 0, 0, -1, 0, -1, -1, -1, 0, 1, -1, -1, -1, -1, 0, -1, 0, 1, -1, -1, -1, 2, 0, -1, -1, 1, 0, -1, 0, -1, -1, -1, 0, 3, -1, -1, -1, -1, 0, 1, -1, 1, -1, -1, 0, 3, 0, -1, -1, 1, -1, -1, 0, -1, -1, -1, 0, 5, 0, -1, -1, -1, -1, -1, 0, 3, 0, -1, 0, 3, -1, -1, -1, 1, 0, 3
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OFFSET
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1,36
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COMMENTS
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In addition to A168645, -1's occur also in the following positions: 256, 512, 6561, 16384, 19683, 32768, 390625, 1048576, ...
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LINKS
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FORMULA
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a(1) = 1; and for n > 2, a(n) = -Sum_{d|n, d<n} a(d) * A005171(n/d).
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PROG
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(PARI)
up_to = 65537;
DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(d<n, v[n/d]*u[d], 0)))); (u) }; \\ Compute the Dirichlet inverse of the sequence given in input vector v.
v346482 = DirInverseCorrect(vector(up_to, n, A005171(n)));
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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