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A117586
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Coefficients of q in series expansion of Zagier's identity.
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0
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0, -1, -2, -1, -1, 2, 0, 4, 1, 2, 1, 2, -4, 1, -1, -5, -2, -1, -3, -1, -2, -2, 5, 0, -1, 1, 8, 0, 3, 2, 2, 2, 3, 0, 4, -7, 0, 0, 2, -3, -8, -2, -1, -3, -2, -4, 0, -3, -3, -2, -1, 7, -1, 0, 1, -1, 0, 12, 2, 2, 0, 4, 3, 4, 0, 2, 4, 3, 0, 5, -12, 2, 0, 1, -1, 1, -3, -11, -1, -2, -6, 2, -4, -3, -3, -4, -2, 1, -5, -3, -3, -2, 11, 2, -2, -3, 2, 0, 0, 3, 12, 1
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OFFSET
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0,3
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LINKS
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FORMULA
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EXAMPLE
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G.f. = - x - 2*x^2 - x^3 - x^4 + 2*x^5 + 4*x^7 + x^8 + 2*x^9 + x^10 + ...
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MATHEMATICA
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Flatten[{0, CoefficientList[Series[-Sum[x^(n - 1)*(QPochhammer[x^(n + 1), x]^2/QPochhammer[x^(n), x]), {n, 1, 101}], {x, 0, 100}], x]}] (* Mats Granvik, Jan 05 2015 *)
a[ n_] := SeriesCoefficient[ Sum[ QPochhammer[ x] - QPochhammer[ x, x, k], {k, 0, n}], {x, 0, n}]; (* Michael Somos, Jan 07 2015 *)
a[ n_] := SeriesCoefficient[ -Sum[ QPochhammer[ x^k, x] x^k / (1 - x^k)^2, {k, n}], {x, 0, n}]; (* Michael Somos, Jan 07 2015 *)
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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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