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A280869
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Expansion of E_6(q)^2 in powers of q.
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17
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1, -1008, 220752, 16519104, 399517776, 4624512480, 34423752384, 187506813312, 814794618960, 2975666040144, 9486668147040, 27052407031104, 70486610910912, 169931677686624, 384163181281152, 820165393918080, 1668889095288912, 3249638073414432
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OFFSET
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0,2
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LINKS
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FORMULA
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E6(q)^2 = (1 - 504 Sum_{i>=1} sigma_5(i)q^i)^2 where sigma_5(n) is A001160.
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EXAMPLE
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G.f. = 1 - 1008*q + 220752*q^2 + 16519104*q^3 + 399517776*q^4 + 4624512480*q^5 + ...
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MATHEMATICA
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terms = 18;
E6[x_] = 1 - 504*Sum[k^5*x^k/(1 - x^k), {k, 1, terms}];
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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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