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A210641
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A117609(n)-A210639(n): Difference between number of lattice points in the ball x^2+y^2+z^2 <= n and the volume of this ball rounded to the nearest integer.
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3
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1, 3, 7, 5, -1, 10, 19, 3, -2, 10, 15, 18, 5, 7, 32, 8, -11, 11, 21, 18, 14, 34, 29, -1, -7, -9, 32, 31, -2, 37, 51, 16, -7, 5, 17, 28, 20, 6, 40, 1, -15, 41, 49, 32, 14, 45, 50, 7, -28, -18, 22, 25, 4, 31, 81, 34, 36, 36, 13, 37, -12, 11, 58, 8, -36, 10, 55
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OFFSET
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0,2
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COMMENTS
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Record values are listed in A000223, and A000092 gives the corresponding indices. Strictly speaking, these are defined using the absolute values, but it appears they always occur at positive elements.
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LINKS
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MATHEMATICA
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a[n_] := Sum[SquaresR[3, k], {k, 0, n}] - Round[(4/3)*Pi*n^(3/2)]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 04 2016 *)
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PROG
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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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