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A117483
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Numbers k for which pi(phi(k)) equals phi(pi(k)).
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0
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0, 1, 3, 4, 5, 8, 10, 11, 17, 20, 22, 30, 31, 41, 50, 59, 67, 75, 83, 109, 127, 157, 174, 179, 191, 200, 211, 241, 277, 283, 331, 353, 360, 367, 401, 414, 431, 460, 461, 475, 509, 547, 563, 587, 599, 617, 709, 739, 773, 797, 859, 877, 919, 942, 960, 967, 991, 1014
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OFFSET
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1,3
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LINKS
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EXAMPLE
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75 is a term because pi(phi(75)) = pi(40) = 12 and phi(pi(75)) = phi(21) = 12;
0 is a term since pi(phi(0)) = pi(0) = 0 and phi(pi(0)) = phi(0) = 0;
1 is a term since pi(phi(1)) = pi(1) = 0 and phi(pi(1)) = phi(0) = 0.
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MAPLE
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with(numtheory): a:=proc(n) if pi(phi(n))=phi(pi(n)) then n else fi end: seq(a(n), n=0..1350); # Emeric Deutsch, Apr 30 2006
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MATHEMATICA
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Select[Range[0, 1030], PrimePi@ EulerPhi@# == EulerPhi@ PrimePi@# &] (* Robert G. Wilson v *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Luc Stevens (lms022(AT)yahoo.com), Apr 25 2006
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EXTENSIONS
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STATUS
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approved
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