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A121287
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Numbers such that Sigma(n)*UnitarySigma(n) is divisible by UnitaryPhi(n)*n.
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1
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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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FORMULA
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PROG
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(PARI) uphi(n) = my(f=factor(n)~); prod(i=1, #f, f[1, i]^f[2, i]-1); \\ A047994
usigma(n) = sumdivmult(n, d, if(gcd(d, n/d)==1, d)); \\ A034448
isok(n) = ((sigma(n)*usigma(n)) % (n*uphi(n))) == 0; \\ Michel Marcus, Jan 24 2019
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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