A069579 - OEIS

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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A069579

Numbers k such that phi(core(k)) = core(phi(k)) where core(k) is the squarefree part of k (the smallest integer such that k*core(k) is a square).

1, 2, 3, 6, 7, 8, 11, 14, 22, 23, 24, 27, 31, 32, 43, 46, 47, 54, 56, 59, 62, 67, 71, 79, 83, 86, 88, 94, 96, 103, 107, 118, 128, 131, 134, 139, 142, 158, 166, 167, 179, 184, 191, 206, 211, 214, 216, 223, 224, 227, 239, 243, 248, 262, 263, 278, 283, 311, 331, 334

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

core[n_] := Times @@ (First[#]^Mod[Last[#], 2]& /@ FactorInteger[n]); Select[Range[300], core[EulerPhi[#]] == EulerPhi[core[#]] &] (* Amiram Eldar, Sep 03 2020 *)

PROG

(PARI) for(n=1, 500, if(core(eulerphi(n))==eulerphi(core(n)), print1(n, ", ")))

CROSSREFS

Cf. A000010, A007913.

Sequence in context: A155152 A098740 A116046 * A327176 A065193 A116047

Adjacent sequences: A069576 A069577 A069578 * A069580 A069581 A069582

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 18 2002

STATUS

approved