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A279289
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Numbers n such that phi(n) > tau(n).
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5
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5, 7, 9, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77
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OFFSET
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1,1
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COMMENTS
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There are 11 numbers n such that phi(n) <= tau(n) and 7 numbers n such that phi(n) = tau(n); see A020490 and A020488.
For n >= 31; phi(n) - tau(n) >= 1, see A063070.
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LINKS
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FORMULA
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a(n) = n + 11 for n >= 20.
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EXAMPLE
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14 is a term because phi(14) = 6 > tau(14) = 4.
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MATHEMATICA
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Select[Range@ 77, EulerPhi@ # > DivisorSigma[0, #] &] (* Michael De Vlieger, Dec 11 2016 *)
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PROG
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(Magma) [n: n in[1..1000] | EulerPhi(n) gt NumberOfDivisors(n)]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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