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A345030
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a(n) = Sum_{k=1..n} n^(floor(n/k) - 1).
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4
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1, 3, 11, 70, 633, 7821, 117709, 2097684, 43047545, 1000010125, 25937439391, 743008621422, 23298085496173, 793714780786669, 29192926036832363, 1152921504875352376, 48661191876077295937, 2185911559749718388655, 104127350297928227579629
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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) = [x^n] (1/(1 - x)) * Sum_{k>=1} x^k * (1 - x^k)/(1 - n*x^k).
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MATHEMATICA
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a[n_] := Sum[n^(Floor[n/k] - 1), {k, 1, n}]; Array[a, 20] (* Amiram Eldar, Jun 06 2021 *)
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PROG
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(PARI) a(n) = sum(k=1, n, n^(n\k-1));
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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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