A362008 - OEIS

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A362008

Numbers whose Euler's cototient is divisible by 9.

21, 27, 34, 54, 63, 68, 78, 81, 106, 108, 115, 117, 126, 129, 135, 136, 142, 147, 156, 162, 171, 178, 183, 186, 187, 189, 195, 205, 210, 212, 214, 216, 234, 237, 243, 252, 270, 272, 279, 284, 291, 295, 297, 312, 315, 324, 333, 342, 351, 356, 358, 372, 378

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

OFFSET

1,1

COMMENTS

Numbers k such that A010888(totient(k)) = A010888(k).

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

Select[Range[2, 400], Mod[#-EulerPhi[#], 9]==0&] (* Harvey P. Dale, Jan 22 2024 *)

PROG

(Python)

from sympy import totient