

A069946


Numbers k such that phi(k) mod core(k) = 1 where core(k) is the squarefree part of k.


1



2, 12, 48, 60, 63, 75, 175, 192, 363, 405, 468, 704, 768, 816, 867, 891, 960, 980, 1008, 1020, 1587, 1875, 2023, 2107, 2331, 2475, 2523, 2527, 2800, 2835, 3072, 3075, 3185, 3332, 3757, 4100, 4335, 4477, 4851, 5043, 5780, 6171, 6292, 6627, 6727, 6877, 7220
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OFFSET

1,1


COMMENTS

This sequence is infinite. For example, 3*4^k is a term for all k > 0, since core(3*4^k) = 3, phi(3*4^k) = 4^k and 4^k == 1 (mod 3).  Amiram Eldar, Sep 03 2020


LINKS



MATHEMATICA

core[n_] := Times @@ (First[#]^Mod[Last[#], 2] & /@ FactorInteger[n]); Select[Range[10^4], Mod[EulerPhi[#], core[#]] == 1 &] (* Amiram Eldar, Sep 03 2020 *)


PROG

(PARI) for(n=1, 15000, if(eulerphi(n)%core(n)==1, print1(n, ", ")))


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



