login
A112587
Numbers m such that phi(m) <= 2*tau(m), where phi=A000010 and tau=A000005.
3
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 28, 30, 36, 40, 42, 48, 60, 72, 84, 90, 120
OFFSET
1,2
COMMENTS
Complement of A112588.
LINKS
Eric Weisstein's World of Mathematics, Totient Function
Eric Weisstein's World of Mathematics, Divisor Function
MATHEMATICA
Select[Range[150], EulerPhi[#]<=2DivisorSigma[0, #]&] (* Harvey P. Dale, Mar 04 2013 *)
PROG
(PARI) is(n)=eulerphi(n)<=2*numdiv(n) \\ Charles R Greathouse IV, Feb 21 2013
CROSSREFS
Cf. A020488.
Sequence in context: A124455 A072378 A248888 * A372916 A068090 A172121
KEYWORD
nonn,fini,full
AUTHOR
Reinhard Zumkeller, Sep 14 2005
STATUS
approved