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Search: id:A070812
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| 0, -1, 2, 0, 3, -1, -1, 2, 5, 0, 9, 3, 2, -1, 14, -1, 15, 2, 3, 5, 11, 0, -1, 9, -1, 3, 21, 2, 25, -1, 5, 14, 3, -1, 33, 15, 9, 2, 35, 3, 35, 5, 1, 11, 23, 0, -1, -1, 14, 9, 39, -1, 5, 3, 15, 21, 29, 2, 55, 25, 3, -1, 9, 5, 55, 14, 11, 3, 63, -1, 69, 33, -1, 15, 5, 9, 65, 2, -1, 35, 41, 3, 14, 35, 21, 5, 77, 1, 9, 11, 25, 23, 15, 0, 93, -1, 5
(list; graph; listen)
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OFFSET
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3,3
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FORMULA
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a(n)=A070777(n)-A068211(n)
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EXAMPLE
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Cases of n when a(n)=1,-1,2 or 0 are listed in A070002, A070003, A070004, A007283 respectively. Further regular solutions: if a(n)=3, then n=7k, where k has prime divisors <7 if a(n)=5, then n=11k, where k has no prime divisors >=11, if a(n)=25, then mostly[not always! ] n=31k...
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MATHEMATICA
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pf[x_] := Part[Reverse[Flatten[FactorInteger[x]]], 2] Table[EulerPhi[pf[u]]-pf[EulerPhi[u]], {u, 3, 128}]
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CROSSREFS
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Cf. A000010, A006530, A070777, A068211, A070002-A070004, A007283.
Sequence in context: A113504 A124754 A047983 this_sequence A061865 A135818 A078804
Adjacent sequences: A070809 A070810 A070811 this_sequence A070813 A070814 A070815
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KEYWORD
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sign
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), May 09 2002
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