The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A070811 Numbers n such that phi(n-phi(n))=A054571(n) is not a power of 2 and n is not a prime number. 3
 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; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..60. EXAMPLE n=30: phi[30]=8, cototient[30]=22,phi[22]=10 is not a power of 2. MATHEMATICA Do[s=EulerPhi[n-EulerPhi[n]]; If[ !IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 256}] CROSSREFS Cf. A054571, A051953, A000010, A070556, A070806-A070810. Sequence in context: A020204 A280389 A057489 * A211375 A326387 A217078 Adjacent sequences: A070808 A070809 A070810 * A070812 A070813 A070814 KEYWORD nonn AUTHOR Labos Elemer, May 08 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 18 21:02 EDT 2024. Contains 374388 sequences. (Running on oeis4.)