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A058267
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An approximation to sigma_{1/2}(n): round( Sum_{ d divides n } sqrt(d) ).
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4
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1, 2, 3, 4, 3, 7, 4, 7, 6, 8, 4, 12, 5, 9, 9, 11, 5, 14, 5, 14, 10, 10, 6, 20, 8, 11, 11, 16, 6, 21, 7, 17, 12, 12, 12, 25, 7, 13, 13, 23, 7, 24, 8, 19, 19, 14, 8, 31, 11, 20, 14, 20, 8, 26, 14, 26, 15, 15, 9, 39, 9, 16, 21, 25, 15, 28, 9, 23, 16, 28, 9, 42, 10
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OFFSET
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1,2
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LINKS
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FORMULA
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Sum_{k=1..n} a(k) ~ (2/3)*zeta(3/2) * n^(3/2). - Amiram Eldar, Jan 14 2023
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MAPLE
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map(round @ numtheory:-sigma[1/2], [$1..100]); # Robert Israel, Aug 18 2017
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MATHEMATICA
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PROG
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(PARI) a(n) = round(sumdiv(n, d, sqrt(d))); \\ Michel Marcus, Aug 17 2017
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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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