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A259695
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a(n) = Sum_{k=1..n-1} k^7 * sigma(k) * sigma(n-k).
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8
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0, 1, 387, 9904, 142475, 850500, 5287786, 19400960, 68736681, 210682950, 565317445, 1328193216, 3163440917, 6945663368, 13045807350, 26914795520, 48673795956, 89900901837, 149363037975, 262436871200, 409003474320, 711715515852, 1035199173422, 1683466675200
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OFFSET
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1,3
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COMMENTS
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LINKS
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MAPLE
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S:=(n, e)->add(k^e*sigma(k)*sigma(n-k), k=1..n-1); f:=e->[seq(S(n, e), n=1..30)]; f(7);
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MATHEMATICA
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Table[Sum[k^7 DivisorSigma[1, k]DivisorSigma[1, n-k], {k, n-1}], {n, 30}] (* Harvey P. Dale, Dec 14 2015 *)
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PROG
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(PARI) a(n) = sum(k=1, n-1, k^7*sigma(k)*sigma(n-k)) \\ Colin Barker, Jul 16 2015
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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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