A358043 Numbers k such that phi(k) is a multiple of 8.

15, 16, 17, 20, 24, 30, 32, 34, 35, 39, 40, 41, 45, 48, 51, 52, 55, 56, 60, 64, 65, 68, 70, 72, 73, 75, 78, 80, 82, 84, 85, 87, 88, 89, 90, 91, 95, 96, 97, 100, 102, 104, 105, 110, 111, 112, 113, 115, 116, 117, 119, 120, 123, 128, 130, 132, 135, 136, 137, 140, 143

Offset

1,1

Links

Table of n, a(n) for n=1..61.

Formula

A000010(a(n)) == 0 (mod 8).

Mathematica

Select[Range[150], Divisible[EulerPhi[#], 8] &] (* Amiram Eldar, Oct 27 2022 *)

Prog

(Python)
from sympy.ntheory import totient
def isok(n): return totient(n) % 8 == 0
(PARI) isok(k) = Mod(eulerphi(k), 8) == 0; \\ Michel Marcus, Oct 27 2022

Crossrefs

Cf. A000010 (phi), A053574 (its 2-adic valuation), A037074 (a subsequence).

Totient multiples: A066498 (3), A172019 (4), A066500 (5), A066502 (7), A332512 (12).

Sequence in context: A297281 A176294 A214424 * A090461 A138598 A281879

Adjacent sequences: A358040 A358041 A358042 * A358044 A358045 A358046

Keyword

nonn

Author

Darío Clavijo, Oct 26 2022

Status

approved