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A356240
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a(n) = Sum_{k=1..n} (k-1)^n * Sum_{j=1..floor(n/k)} j^n.
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1
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0, 1, 9, 114, 1332, 25404, 395460, 9724901, 207584371, 6120938951, 151737244257, 5932533980409, 168400694345669, 7145593797561899, 260681076993636793, 12410128414690753548, 473029927456547840472, 27572016889372245275679
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) = Sum_{k=1..n} k^n * (sigma_0(k) - floor(n/k)^n) = A356239(n) - A356238(n).
a(n) = Sum_{k=1..n} k^n * Sum_{d|k} (1 - 1/d)^n.
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MATHEMATICA
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a[n_] := Sum[(k - 1)^n * Sum[j^n, {j, 1, Floor[n/k]}], {k, 1, n}]; Array[a, 18] (* Amiram Eldar, Jul 30 2022 *)
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PROG
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(PARI) a(n) = sum(k=1, n, (k-1)^n*sum(j=1, n\k, j^n));
(PARI) a(n) = sum(k=1, n, k^n*(sigma(k, 0)-(n\k)^n));
(PARI) a(n) = sum(k=1, n, k^n*sumdiv(k, d, (1-1/d)^n));
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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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