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A082070
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Least common prime-divisor of Phi[n] and Sigma[1,n]=A000203(n); a(n)=1 if no common prime-divisor was found.
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0
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1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 3, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 1, 2, 2, 2, 2, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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MATHEMATICA
| ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] f1[x_] := EulerPhi[x]; f2[x_] := DivisorSigma[1, x] Table[Min[Intersection[ba[f1[w]], ba[f2[w]]]], {w, 1, 128}]
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CROSSREFS
| Cf. A000010, A000203, A082061-A082072.
Sequence in context: A105307 A082071 A082065 * A082902 A123926 A082064
Adjacent sequences: A082067 A082068 A082069 * A082071 A082072 A082073
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Apr 07 2003
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