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Search: id:A125749
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| A125749 |
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a(n) is the smallest positive integer such that (sum{1<=k<=a(n), GCD(t(k),n)=1} t(k)) is >= n, where t(k) is the k-th positive integer which is coprime to n. |
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3
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| 1, 2, 2, 2, 3, 2, 4, 3, 4, 3, 5, 3, 5, 4, 5, 4, 6, 4, 6, 4, 6, 5, 7, 4, 7, 6, 6, 5, 8, 4, 8, 6, 7, 6, 8, 5, 9, 7, 8, 6, 9, 5, 9, 7, 7, 7, 10, 6, 10, 7, 9, 8, 10, 6, 10, 7, 9, 8, 11, 6, 11, 8, 9, 8, 11, 7, 12, 9, 10, 7, 12, 7, 12, 9, 9, 9, 12, 7, 13, 8, 11, 10, 13, 7, 12, 10, 11, 9, 13, 7, 13, 10, 12
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OFFSET
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1,2
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EXAMPLE
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The positive integers which are coprime to 12 are 1,5,7,11,13,... Now 1+5 = 6, which is less than 12; but 1+5+7 is 13, which is >= 12. 7 is the 3rd positive integer which is coprime to 12, so a(12) = 3.
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MATHEMATICA
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f[n_] := Block[{k = 1, l}, While[l = Select[Range[k], GCD[ #, n] == 1 &]; Plus @@ l < n, k++ ]; Length[l]]; Table[f[n], {n, 100}] (*Chandler*)
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CROSSREFS
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Cf. A125748, A117893.
Adjacent sequences: A125746 A125747 A125748 this_sequence A125750 A125751 A125752
Sequence in context: A036013 A126336 A134446 this_sequence A014085 A029210 A035433
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Dec 06 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 11 2006
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