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A238983
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Numbers n such that the sum of n-th powers of unitary divisors of n is congruent to -1 modulo n.
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2
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OFFSET
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1,2
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COMMENTS
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LINKS
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MATHEMATICA
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AA[n_, k_] := AA[n, k] = Mod[Sum[If[GCD[i, n] == i && GCD[i, n/i] == 1, PowerMod[i, k, n], 0], {i, n}], n]; Select[Range[1000], Mod[AA[#, #], #] == #-1 &]
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PROG
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(PARI) isok(n) = (sumdiv(n, d, d^n*(gcd(d, n/d) == 1)) % n) == (n-1); \\ Michel Marcus, Sep 30 2014
(PARI) isok(n) = sumdiv(n, d, if (gcd(d, n/d) == 1, Mod(d, n)^n)) == Mod(n-1, n); \\ Michel Marcus, Oct 02 2014
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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