A307579 - OEIS

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A307579

Numbers k such that A003958(k) does not divide phi(k).

9, 18, 25, 27, 45, 49, 50, 54, 63, 75, 81, 90, 98, 99, 100, 108, 117, 121, 125, 126, 135, 147, 150, 153, 156, 162, 169, 171, 175, 189, 196, 198, 207, 225, 234, 242, 243, 245, 250, 261, 270, 275, 279, 289, 294, 297, 300, 306, 315, 324, 325, 333, 338, 342, 343, 350, 351, 361, 363

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

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..59.

EXAMPLE

For n = 1 the a(1) = 9 because A003958(9) = 4 does not divide A000010(9) = 6.

MATHEMATICA

Select[Range[2, 363], Mod[EulerPhi@ #, Times @@ Map[# /. {p_, e_} :> (p - 1)^e &, FactorInteger[#]]] != 0 &] (* Michael De Vlieger, Apr 21 2019 *)

CROSSREFS

Contained in A013929.

Cf. A000010, A003557, A003958, A007947, A005117, A319927.