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Search: id:A110196
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| A110196 |
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Numbers n such that k=2n is the least k such that phi(n+k)=2*phi(k). |
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+0
2
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| 1, 13, 23, 97, 113, 131, 199, 227, 491, 859, 929
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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No other n < 10^6. Note that all n>1 are primes.
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MATHEMATICA
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Do[k=1; While[EulerPhi[n+k] != 2*EulerPhi[k], k++ ]; If[k==2n, Print[n]], {n, 5000}]
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CROSSREFS
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Cf. A050473 (least k such that phi(n+k)=2*phi(k)).
Sequence in context: A155093 A147443 A131447 this_sequence A111943 A039448 A089768
Adjacent sequences: A110193 A110194 A110195 this_sequence A110197 A110198 A110199
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Jul 15 2005
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