The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A296214 Numbers n for which there is at least one x < n such that phi(x) = phi(n). 4
 2, 4, 6, 8, 9, 10, 12, 14, 16, 18, 20, 21, 22, 24, 26, 27, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 66, 68, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 86, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n for which A081373(n) > 1. Apart from the initial term 2, this is the complement of union of A000040 (primes) and A069823. LINKS Antti Karttunen, Table of n, a(n) for n = 1..12973 PROG (PARI) for(n=1, 200, y=0; s=eulerphi(n); for(k=1, (n-1), if(eulerphi(k)==s, y=1; break)); if(y, print1(n, ", "))); CROSSREFS Cf. A000010, A069822, A069823, A081373. Cf. A296087 (a subsequence). Sequence in context: A355670 A336375 A353683 * A325572 A337945 A247423 Adjacent sequences: A296211 A296212 A296213 * A296215 A296216 A296217 KEYWORD nonn AUTHOR Antti Karttunen, Dec 08 2017 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 May 25 17:00 EDT 2024. Contains 372804 sequences. (Running on oeis4.)