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Numbers divisible by 2 or more primitive nondeficient numbers.
4

%I #25 Oct 24 2020 17:24:27

%S 60,84,120,140,168,180,210,240,252,264,280,300,312,336,360,420,440,

%T 480,504,520,528,540,560,588,600,616,624,630,660,672,700,720,728,756,

%U 780,792,816,840,880,900,912,924,936,960,980,1008,1020,1040,1050,1056,1080,1092

%N Numbers divisible by 2 or more primitive nondeficient numbers.

%C A006039 lists the primitive nondeficient numbers.

%C The first odd term is 4725.

%H David A. Corneth, <a href="/A337688/b337688.txt">Table of n, a(n) for n = 1..10000</a>

%H David A. Corneth, <a href="/A337688/a337688_1.gp.txt">PARI program</a>

%F Numbers k such that A337690(k) >= 2.

%e Table of n, a(n) and the relevant divisors starts:

%e n a(n) divisors in A006039

%e 1 60 6, 20;

%e 2 84 6, 28;

%e 3 120 6, 20;

%e 4 140 20, 28, 70;

%e 5 168 6, 28;

%e 6 180 6, 20;

%e 7 210 6, 70;

%e 8 240 6, 20;

%e 9 252 6, 28;

%e 10 264 6, 88;

%e 11 280 20, 28, 70;

%e 12 300 6, 20;

%e 13 312 6, 104;

%e 14 336 6, 28;

%e 15 360 6, 20;

%e 16 420 6, 20, 28, 70;

%o (PARI) See Corneth link \\ _David A. Corneth_, Oct 07 2020

%Y A006039 is used to define this sequence.

%Y Subsequence of: A091192.

%Y A337689 is a subsequence.

%Y A337690 is used in a formula defining this sequence.

%K nonn,easy

%O 1,1

%A _David A. Corneth_, _Antti Karttunen_ and _Peter Munn_, Sep 20 2020