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A292560
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Expansion of Product_{k>=1} 1/(1 + x^(k^3)).
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3
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1, -1, 1, -1, 1, -1, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 1, -1, 1, -1, 1, -1, 0, 0, 0, -1, 1, -1, 1, -1, 2, -2, 2, -1, 1, -1, 1, -1, 0, 0, 0, -1, 1, -1, 1, -1, 2, -2, 2, -1, 1, -1, 2, -2, 1, -1, 1, -2, 2, -2, 1, -1, 1, -1, 1, 0, 0, 0, 1, -1, 1, -1, 1, -2, 2, -2, 1, -1, 1, -2, 2, -1, 1, -1, 2, -2, 2, -1, 1
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OFFSET
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0,33
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COMMENTS
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The difference between the number of partitions of n into an even number of cubes and the number of partitions of n into an odd number of cubes.
In general, if m > 0 and g.f. = Product_{k>=1} 1/(1 + x^(k^m)), then a(n) ~ (-1)^n * exp((m+1) * (Gamma(1/m) * Zeta(1 + 1/m) / m^2)^(m/(m+1)) * n^(1/(m+1)) / 2) * (Gamma(1/m) * Zeta(1 + 1/m))^(m/(2*(m+1))) / (sqrt(Pi*(m+1)) * 2^((m+1)/2) * m^((m-1)/(2*(m+1))) * n^((2*m+1)/(2*(m+1)))). - Vaclav Kotesovec, Sep 19 2017
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LINKS
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FORMULA
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G.f.: Product_{k>=1} 1/(1 + x^(k^3)).
a(n) ~ (-1)^n * exp(2 * (Gamma(1/3) * Zeta(4/3))^(3/4) * n^(1/4) / 3^(3/2)) * (Gamma(1/3) * Zeta(4/3))^(3/8) / (8 * 3^(1/4) * sqrt(Pi) * n^(7/8)). - Vaclav Kotesovec, Sep 19 2017
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MATHEMATICA
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nmax = 100; CoefficientList[Series[Product[1/(1 + x^(k^3)), {k, 1, Floor[nmax^(1/3)] + 1}], {x, 0, nmax}], x]
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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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