OFFSET
1,1
COMMENTS
Almost all composite numbers k such that phi(k) > 2k/3 have no prime factor among 2 and 3.
LINKS
Marius A. Burtea, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Flatten @ Table[6*n + {1, 5}, {n, 0, 2500}], CompositeQ[#] && EulerPhi[#] < 2*#/3 &] (* Amiram Eldar, Jun 09 2022 *)
PROG
(PARI) lista(nn) = {forcomposite(n=1, nn, if ((gcd(n, 6) == 1) && (n/eulerphi(n) > 3/2), print1(n, ", ")); ); } \\ Michel Marcus, Jul 05 2015
(Magma) [k:k in [1..14000]| not IsPrime(k) and Gcd(6, k) eq 1 and EulerPhi(k) lt 2*k/3]; // Marius A. Burtea, Oct 01 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 03 2002
STATUS
approved