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A055412
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Number of points in Z^6 of norm <= n.
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6
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1, 13, 485, 4197, 23793, 84769, 252673, 622573, 1395261, 2787125, 5260181, 9249417, 15637897, 25112577, 39258381, 59174749, 87380293, 125264525, 176663297, 244000537, 332379769, 444344469, 587923621, 766764301, 990981473
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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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a(n) = A122510(6,n^2). - _R. J. Mathar_, Apr 21 2010
a(n) = [x^(n^2)] theta_3(x)^6/(1 - x), where theta_3() is the Jacobi theta function. - _Ilya Gutkovskiy_, Apr 14 2018
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MATHEMATICA
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t[d_, n_] := t[d, n] = t[d, n - 1] + SquaresR[d, n]; t[d_, 0] = 1;
a[n_] := t[6, n^2];
a /@ Range[0, 100] (* _Jean-François Alcover_, Sep 27 2019, after _R. J. Mathar_ *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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_David W. Wilson_
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STATUS
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approved
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