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A297793
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a(n) = Sum_{d|n} min(d, n/d)^3.
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5
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1, 2, 2, 10, 2, 18, 2, 18, 29, 18, 2, 72, 2, 18, 56, 82, 2, 72, 2, 146, 56, 18, 2, 200, 127, 18, 56, 146, 2, 322, 2, 146, 56, 18, 252, 416, 2, 18, 56, 396, 2, 504, 2, 146, 306, 18, 2, 632, 345, 268, 56, 146, 2, 504, 252, 832, 56, 18, 2, 882, 2, 18, 742, 658, 252
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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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a(n) = - Sum_{k in Z} (k^2-n)*H(4*n-k^2) where H() is the Hurwitz class number.
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MATHEMATICA
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a[n_] := DivisorSum[n, Min[#, n/#]^3 &]; Array[a, 65] (* Amiram Eldar, Oct 04 2023*)
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PROG
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(PARI) {a(n) = sumdiv(n, d, min(d, n/d)^3)}
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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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