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A147802
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Least m coprime to 3 minimizing A007947(m*(3^n-m)).
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6
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1, 1, 2, 1, 1, 25, 139, 289, 31, 1, 16096, 49, 7424, 588665, 619115, 83521, 8000000, 1515625, 505620842, 17643776, 244140625, 5443635008
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OFFSET
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1,3
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COMMENTS
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Related to the abc conjecture: Since m is coprime to 3, it is also coprime to 3^n and thus to 3^n-m. Thus A007947(m*(3^n-m)*3^n) = 3*A007947(m(3^n-m)).
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LINKS
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MATHEMATICA
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rad[n_] := Times @@ FactorInteger[n][[All, 1]];
a[n_] := MinimalBy[Select[Range[3^n - 2], CoprimeQ[#, 3] &], rad[# (3^n - #)] &][[1]];
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PROG
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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