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A245047
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Numbers n where phi(n)|n or tau(n)|n.
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1
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1, 2, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 40, 48, 54, 56, 60, 64, 72, 80, 84, 88, 96, 104, 108, 128, 132, 136, 144, 152, 156, 162, 180, 184, 192, 204, 216, 225, 228, 232, 240, 248, 252, 256, 276, 288, 296, 324, 328, 344, 348, 360, 372, 376, 384, 396, 424, 432, 441, 444, 448, 450
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OFFSET
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1,2
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COMMENTS
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Phi(n) is Euler totient function (A000010); tau(n) is the number of divisors of n (A000005).
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LINKS
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MAPLE
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select(t -> (t mod numtheory:-phi(t) = 0) or (t mod numtheory:-tau(t) = 0), [$1..1000]); # Robert Israel, Jul 15 2014
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MATHEMATICA
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Select[Range[500], AnyTrue[{#/EulerPhi[#], #/DivisorSigma[0, #]}, IntegerQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 12 2020 *)
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PROG
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(PARI) isok(n) = !((n % eulerphi(n)) && (n % numdiv(n))); \\ Michel Marcus, Jul 15 2014
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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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