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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
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. A296087 (a subsequence).
Sequence in context: A355670 A336375 A353683 * A325572 A337945 A247423
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 08 2017
STATUS
approved

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Last modified May 25 17:00 EDT 2024. Contains 372804 sequences. (Running on oeis4.)