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A332838
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Numbers k such that -tau(k)^2 == tau(k) mod k where tau = A000005.
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0
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OFFSET
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1,2
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LINKS
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EXAMPLE
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24 is in this sequence because tau(24) = 8 and -8^2 mod 24 = 8.
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MAPLE
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q:= n-> (t-> irem(t^2+t, n)=0)(numtheory[tau](n)):
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MATHEMATICA
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Select[Range[1000], Divisible[(d = DivisorSigma[0, #]) + d^2, #] &] (* Amiram Eldar, Feb 26 2020 *)
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PROG
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(PARI) isok(m) = my(nd=numdiv(m)); Mod(-nd^2, m) == nd; \\ Michel Marcus, Feb 26 2020
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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