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A244324
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Numbers n such that floor(antisigma(n) / n) = antisigma(n) mod n.
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2
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1, 2, 15, 20, 104, 207, 464, 650, 1023, 1952, 2975, 19359, 130304, 147455, 522752, 1207359, 5017599, 8382464
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OFFSET
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1,2
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COMMENTS
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Antisigma(n) = A024816(n) = sum of numbers less than n which do not divide n.
Also numbers n such that there is some number k > 0 with property: antisigma(n) = k*(n+1). Corresponding values of numbers k: 0, 0, 6, 8, 50, 102, 230, 323, 510, 974, 1486, 9678, …
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LINKS
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EXAMPLE
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Antisigma(19359) = 187366080 = 9678*19359 + 9678.
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PROG
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(Magma) [n: n in [1..1000000] | u eq 0 where u is (Floor((((n*(n+1)) div 2 - SumOfDivisors(n)) div n))) - (((((n*(n+1)) div 2)-SumOfDivisors(n)) mod (n)))]
(PARI) isok(n) = my(as = n*(n+1)/2 - sigma(n)); (as\n == as % n); \\ Michel Marcus, Jun 26 2014
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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