The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 15 04:47 EDT 2021. Contains 345043 sequences. (Running on oeis4.)