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Search: id:A055744
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| A055744 |
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Numbers n such that n and EulerPhi(n) have same prime factors. |
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+0
5
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| 4, 8, 16, 18, 32, 36, 50, 54, 64, 72, 100, 108, 128, 144, 162, 200, 216, 250, 256, 288, 294, 324, 400, 432, 450, 486, 500, 512, 576, 578, 588, 648, 800, 864, 882, 900, 972, 1000, 1014, 1024, 1152, 1156, 1176, 1210, 1250, 1296, 1350, 1458, 1600, 1728, 1764
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OFFSET
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1,1
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COMMENT
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Contains products of suitable powers of 2 and Fermat primes. For x=2^u.3^w, Phi(x)=2^u.3^(w-1) with suitable exponents. Analogous constructions are possible with {2,3,7} prime divisors, etc.
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EXAMPLE
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n=578=2.17.17, Phi(578)=272=2.2.2.2.17 with 2 and 17 prime-factors n=588=2.2.3.7.7, Phi(588)=168=2.2.2.3.7 n=264196=2.2.257.257, Phi(264196)=512.257=131584
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CROSSREFS
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Cf. A001221, A000010.
Sequence in context: A065192 A161994 A070738 this_sequence A141718 A033310 A104235
Adjacent sequences: A055741 A055742 A055743 this_sequence A055745 A055746 A055747
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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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EXTENSIONS
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Corrected and extended by James A. Sellers (sellersj(AT)math.psu.edu), Jul 11 2000
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