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Numbers divisible by 3 or more primitive nondeficient numbers.
4

%I #17 Oct 19 2020 04:23:29

%S 140,280,420,560,700,840,980,1120,1144,1260,1320,1400,1540,1560,1680,

%T 1820,1848,1890,1960,2100,2184,2200,2240,2288,2380,2520,2600,2640,

%U 2660,2800,2860,2940,2992,3080,3120,3150,3220,3300,3344,3360,3432,3500,3640,3696,3740

%N Numbers divisible by 3 or more primitive nondeficient numbers.

%C A006039 lists the primitive nondeficient numbers.

%H David A. Corneth, <a href="/A337689/b337689.txt">Table of n, a(n) for n = 1..10000</a>

%H David A. Corneth, <a href="/A337689/a337689.gp.txt">PARI program</a>

%F Numbers k such that A337690(k) >= 3.

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

%e n a(n) divisors in A006039

%e 1 140 20, 28, 70;

%e 2 280 20, 28, 70;

%e 3 420 6, 20, 28, 70;

%e 4 560 20, 28, 70;

%e 5 700 20, 28, 70;

%e 6 840 6, 20, 28, 70;

%e 7 980 20, 28, 70;

%e 8 1120 20, 28, 70;

%e 9 1144 88, 104, 572;

%e 10 1260 6, 20, 28, 70;

%e 11 1320 6, 20, 88;

%e 12 1400 20, 28, 70;

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

%Y A006039, A337690 are used in a definition of this sequence.

%Y Subsequence of: A337688.

%K nonn,easy

%O 1,1

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