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Search: id:A074919
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| A074919 |
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Number of integers in {1, 2, ..., phi(n)} that are coprime to n. |
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4
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| 1, 1, 2, 1, 4, 1, 6, 2, 4, 2, 10, 1, 12, 3, 5, 4, 16, 2, 18, 3, 7, 5, 22, 3, 16, 6, 12, 5, 28, 2, 30, 8, 13, 8, 17, 4, 36, 9, 15, 6, 40, 3, 42, 9, 13, 11, 46, 5, 36, 8, 21, 11, 52, 6, 29, 10, 23, 14, 58, 4, 60, 15, 20, 16, 36, 6, 66, 15, 29, 8, 70, 8, 72, 18, 21, 17, 47, 7, 78, 13, 36
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Compare the definition of a(n) to phi(n) = number of integers in {1, 2, ..., n} that are coprime to n.
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EXAMPLE
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There are four numbers in {1, 2, ..., phi(8) = 4} that are coprime to 8, i.e. 1, 3. Hence a(8) = 2.
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MATHEMATICA
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h[n_] := Module[{l}, l = {}; For[i = 1, i <= EulerPhi[n], i++, If[GCD[i, n] == 1, l = Append[l, i]]]; l]; Table[Length[h[i]], {i, 1, 100}]
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CROSSREFS
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Sequence in context: A130892 A074643 A060794 this_sequence A138009 A131755 A118275
Adjacent sequences: A074916 A074917 A074918 this_sequence A074920 A074921 A074922
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 04 2002
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