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A285797
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Number of ways to write n as an ordered sum of two numbers that are the product of an odd number of distinct primes.
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2
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0, 0, 0, 0, 1, 2, 1, 2, 2, 2, 3, 0, 2, 2, 3, 2, 4, 0, 4, 2, 4, 2, 5, 0, 6, 2, 5, 0, 4, 0, 6, 2, 6, 4, 7, 2, 8, 2, 3, 2, 6, 2, 8, 4, 8, 4, 7, 4, 10, 6, 8, 0, 6, 4, 10, 4, 6, 0, 7, 4, 13, 6, 5, 2, 10, 2, 12, 2, 6, 4, 10, 6, 16, 10, 9, 4, 10, 6, 14, 4, 10, 6, 9, 10, 17, 8, 9, 2, 8, 10, 18, 6, 8, 2, 9, 6, 16, 6, 6, 4, 14
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OFFSET
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0,6
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COMMENTS
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Conjecture: a(n) > 0 for all n > 57.
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LINKS
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FORMULA
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EXAMPLE
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a(10) = 3 because we have [7, 3], [5, 5] and [3, 7].
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MATHEMATICA
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nmax = 100; CoefficientList[Series[(Sum[Boole[MoebiusMu[k] == -1] x^k, {k, 1, nmax}])^2, {x, 0, nmax}], x]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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