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Search: id:A055742
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| A055742 |
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Numbers n such that n and EulerPhi(n) have same number of prime factors. |
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+0
1
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| 1, 3, 4, 5, 8, 14, 16, 17, 18, 21, 22, 26, 28, 32, 33, 35, 36, 38, 39, 44, 45, 46, 50, 52, 54, 55, 56, 57, 58, 63, 64, 65, 69, 72, 74, 75, 76, 82, 87, 88, 91, 92, 94, 95, 100, 104, 106, 108, 111, 112, 115, 116, 117, 118, 119, 123, 128, 133, 135, 141, 144, 145, 146, 148
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OFFSET
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1,2
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FORMULA
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A001221(A000010(n)) = A001221(n)
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EXAMPLE
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3 and 5 known Fermat-primes belong here because their Phi is divided only by 2. Several composites are also here, like {50,999,1000} with (2,5),(3,37) and (2,5) prime divisors and their phi,{20,648,400} have also 2 factors: (2,5),(2,3),(2,5)
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CROSSREFS
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Cf. A001221, A000010.
Sequence in context: A030403 A034403 A039020 this_sequence A106048 A049931 A058983
Adjacent sequences: A055739 A055740 A055741 this_sequence A055743 A055744 A055745
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jul 11 2000
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