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%I #22 Oct 15 2020 05:19:30
%S 105,165,195,315,495,525,585,735,825,945,975,1155,1365,1485,1575,1755,
%T 1785,1815,1995,2145,2205,2415,2475,2535,2625,2805,2835,2925,3003,
%U 3045,3135,3255,3315,3465,3675,3705,3795,3885,3927,4095,4125,4305,4389,4455
%N Odd n such that 2*phi(n) < n.
%C Obviously 2*phi(n) = n is impossible for odd n. Odd elements of A054741 and A119432. This is not the same as A036798. 684411 = 3*7*13*23*109 is in this sequence but not in A036798. (This is may not be the smallest such value.) The primitive elements of this sequence are A119433, excluding the initial 2
%C If n is in the sequence, then so is every odd multiple of n. - _Robert Israel_, Jan 06 2017
%C The asymptotic density of this sequence is in the interval (0.01120, 0.01176) (Kobayashi, 2016). It is 1/2 less than the asymptotic density of A119432. The number of terms below 10^k for k = 3, 4, ... are 11, 109, 1152, 11076, 111927, 1124091, 11224403, 112074112, ... - _Amiram Eldar_, Oct 15 2020
%H Robert Israel, <a href="/A119434/b119434.txt">Table of n, a(n) for n = 1..10000</a>
%H Mitsuo Kobayashi, <a href="https://doi.org/10.1142/S1793042116500445">A generalization of a series for the density of abundant numbers</a>, International Journal of Number Theory, Vol. 12, No. 3 (2016), pp. 671-677.
%F A036798 UNION A118700. - _R. J. Mathar_, Aug 08 2007
%F A119432 \ A299174. - _Amiram Eldar_, Oct 15 2020
%p select(t -> numtheory:-phi(t) < t/2, [seq(t,t=1..10000,2)]);
%t Select[Range[1, 10^4, 2], 2 EulerPhi[#] < #&] (* _Jean-François Alcover_, Apr 12 2019 *)
%o (PARI) lista(nn) = forstep (n=1, nn, 2, if (n > 2*eulerphi(n), print1(n, ", "))) \\ _Michel Marcus_, Jul 04 2015
%Y Cf. A000010, A036798, A054741, A118700, A119432, A119433, A299174.
%K nonn
%O 1,1
%A _Franklin T. Adams-Watters_, May 19 2006
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