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A135239
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Numbers n such that sigma(phi(n))=2n.
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1
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OFFSET
| 1,1
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COMMENTS
| No other terms below 10^10.
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EXAMPLE
| sigma(phi(222850677))=sigma(118879488)=445701354=2*222850677, so 222850677 is in the sequence.
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MATHEMATICA
| Do[If[DivisorSigma[1, EulerPhi[n]]==2n, Print[n]], {n, 420000000}]
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CROSSREFS
| Cf. A135240.
Sequence in context: A190031 A187862 A186864 * A046043 A138480 A047627
Adjacent sequences: A135236 A135237 A135238 * A135240 A135241 A135242
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KEYWORD
| more,nonn
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AUTHOR
| Farideh Firoozbakht (mymontain(AT)yahoo.com), Dec 26 2007
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EXTENSIONS
| Search extended to 10^10 by Max Alekseyev (maxale(AT)gmail.com), Sep 25 2009
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