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A358043 Numbers k such that phi(k) is a multiple of 8. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
Darío Clavijo, Oct 26 2022
STATUS
approved

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Last modified March 1 20:05 EST 2024. Contains 370443 sequences. (Running on oeis4.)