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Search: id:A092585
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| A092585 |
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Numbers n such that sigma[phi(n)]-phi[sigma(n)] is nonzero and is divisible by (n-1), that is A065395[n]/(n-1)=phi[sigma(n)]-sigma[phi(n)]/(n-1) is a nonzero integer. |
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+0
2
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| 2, 4, 16, 64, 151, 449, 3403, 4096, 4267, 9307, 35905, 65536, 247285, 262144, 17625601, 33126625
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OFFSET
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1,1
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EXAMPLE
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sigma(phi(x))-phi(sigma(x))/(x-1) is -1 if x=2,4,16,64,4096,65536,262144 and is 2 if x=151,449,3403, etc.
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MATHEMATICA
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f[ x_] := EulerPhi[ DivisorSigma[1, x]] - DivisorSigma[1, EulerPhi[x]]; t = {}; Do[ s = f[n]; If[ s != 0 && Mod[ s, n - 1] == 0, Print[n]; AppendTo[t, n], {n, 2*10^8}]; t
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CROSSREFS
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Cf. A033632, A092584-A092588, A065395.
Sequence in context: A138871 A001901 A127588 this_sequence A106186 A001900 A113247
Adjacent sequences: A092582 A092583 A092584 this_sequence A092586 A092587 A092588
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Mar 01 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) Mar 03 2004
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