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A298330
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Number of ordered ways of writing n^2 as a sum of n squares of positive integers.
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13
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1, 1, 0, 3, 1, 5, 141, 742, 6120, 43888, 300232, 3074478, 28901797, 290411147, 3175037698, 34951274416, 399750066121, 4814421349467, 59532792202344, 768079420764884, 10247011240209066, 140144002390928732, 1978092111496441512, 28633995987157024399
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = [x^(n^2)] (Sum_{k>=1} x^(k^2))^n.
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EXAMPLE
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a(3) = 3 because we have [4, 4, 1], [4, 1, 4] and [1, 4, 4].
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MATHEMATICA
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Table[SeriesCoefficient[(-1 + EllipticTheta[3, 0, x])^n/2^n, {x, 0, n^2}], {n, 0, 23}]
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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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