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A082072
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Least common prime-divisor of Sigma[1,n]=A000203(n) and Sigma[2,n]=A001157(n); a(n)=1 if no common prime-divisor was found.
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6
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1, 1, 2, 7, 2, 2, 2, 5, 13, 2, 2, 2, 2, 2, 2, 31, 2, 13, 2, 2, 2, 2, 2, 2, 31, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 127, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 2, 2, 2, 2, 11, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 7, 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_] := DivisorSigma[1, x]; f2[x_] := DivisorSigma[2, x] Table[Min[Intersection[ba[f1[w]], ba[f2[w]]]], {w, 1, 128}]
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CROSSREFS
| Cf. A000203, A001157, A082061-A082072.
Sequence in context: A072981 A023399 A195476 * A082066 A179931 A130335
Adjacent sequences: A082069 A082070 A082071 * A082073 A082074 A082075
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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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