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A070811
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Numbers n such that phi(n-phi(n))=A054571(n) is not a power of 2 and n is not a prime number.
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3
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1, 15, 21, 26, 27, 30, 33, 34, 35, 45, 49, 51, 52, 54, 57, 60, 63, 66, 68, 69, 70, 74, 75, 78, 81, 82, 85, 86, 87, 90, 91, 93, 95, 98, 99, 102, 104, 105, 106, 108, 110, 111, 114, 115, 117, 119, 120, 121, 122, 123, 125, 126, 129, 130, 132, 133, 135, 136, 138, 140
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| n=30: phi[30]=8, cototient[30]=22,phi[22]=10 is not a power of 2.
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MATHEMATICA
| Do[s=EulerPhi[n-EulerPhi[n]]; If[ !IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 256}]
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CROSSREFS
| Cf. A054571, A051953, A000010, A070556, A070806-A070810.
Sequence in context: A129926 A020204 A057489 * A138594 A131651 A134642
Adjacent sequences: A070808 A070809 A070810 * A070812 A070813 A070814
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 08 2002
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