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A232324
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n(n+1)/2 modulo sigma(n).
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11
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0, 0, 2, 3, 3, 9, 4, 6, 6, 1, 6, 22, 7, 9, 0, 12, 9, 15, 10, 0, 7, 1, 12, 0, 15, 15, 18, 14, 15, 33, 16, 24, 33, 1, 6, 29, 19, 21, 52, 10, 21, 39, 22, 66, 21, 1, 24, 60, 28, 66, 30, 6, 27, 45, 28, 36, 53, 1, 30, 150, 31, 33, 40, 48, 45, 51, 34, 78, 15, 37, 36
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OFFSET
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1,3
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COMMENTS
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Also antisigma(n) modulo sigma(n). Antisigma(n) = A024816(n) = the sum of the nondivisors of n that are between 1 and n, sigma(n) = A000203(n) = the sum of the divisors of n.
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LINKS
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FORMULA
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EXAMPLE
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For n=10, a(10) = antisigma(10) mod sigma(10) = 37 mod 18 = 1.
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MATHEMATICA
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Table[Mod[n (n + 1)/2, DivisorSigma[1, n]], {n, 100}] (* T. D. Noe, Nov 27 2013 *)
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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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