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A069043 Composite numbers k with no prime factor among (2, 3) (cf. A038509) and such that phi(k) < 2*k/3. 3
385, 455, 595, 665, 805, 1015, 1085, 1925, 2275, 2695, 2975, 3185, 3325, 4025, 4165, 4235, 4655, 5005, 5075, 5425, 5635, 5915, 6545, 7105, 7315, 7595, 7735, 8645, 8855, 9625, 10115, 10465, 11165, 11305, 11375, 11935, 12155, 12635, 13195, 13475 (list; graph; refs; listen; history; text; internal format)
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

FORMULA

A038509 SETMINUS A067793: numbers in A038509 but not in A067793.

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

Cf. A038509, A067793.

Sequence in context: A254352 A274445 A227974 * A013591 A152941 A229853

Adjacent sequences:  A069040 A069041 A069042 * A069044 A069045 A069046

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 03 2002

STATUS

approved

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Last modified June 4 18:21 EDT 2020. Contains 334828 sequences. (Running on oeis4.)