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A143973
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Distances between multiples of 3 in A000010.
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1
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2, 4, 1, 4, 1, 2, 5, 1, 1, 3, 4, 1, 1, 1, 1, 3, 1, 2, 4, 3, 2, 2, 1, 4, 1, 1, 2, 2, 3, 2, 1, 1, 2, 1, 1, 1, 2, 3, 2, 4, 1, 2, 2, 2, 1, 1, 4, 1, 1, 3, 1, 2, 1, 2, 3, 2, 3, 2, 2, 1, 2, 1, 3, 1, 1, 4, 1, 3, 1, 2, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 5, 1, 2, 1
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OFFSET
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1,1
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COMMENTS
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Inspired by the question: is n == 1 mod phi(n) for n composite?
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LINKS
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FORMULA
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a(1) = 2 since the first two numbers k such that 3 | phi(k) are 7 and 9, and 9 - 7 = 2.
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MATHEMATICA
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Differences @ Position[EulerPhi[Range[200]], _?(Divisible[#, 3] &)] // Flatten (* Amiram Eldar, Feb 29 2020 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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J. Perry (johnandruth(AT)jrperry.orangehome.co.uk), Sep 06 2008
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EXTENSIONS
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Offset corrected and more terms added by Amiram Eldar, Feb 29 2020
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STATUS
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approved
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