A337689 Numbers divisible by 3 or more primitive nondeficient numbers.

140, 280, 420, 560, 700, 840, 980, 1120, 1144, 1260, 1320, 1400, 1540, 1560, 1680, 1820, 1848, 1890, 1960, 2100, 2184, 2200, 2240, 2288, 2380, 2520, 2600, 2640, 2660, 2800, 2860, 2940, 2992, 3080, 3120, 3150, 3220, 3300, 3344, 3360, 3432, 3500, 3640, 3696, 3740

Offset: 1

Author

David A. Corneth, Antti Karttunen and Peter Munn, Sep 20 2020

Keywords

• nonn
• easy

Comments

A006039 lists the primitive nondeficient numbers.

Examples

			Table of n, a(n) and the relevant divisors starts:
   n   a(n)   divisors in A006039
   1    140   20, 28, 70;
   2    280   20, 28, 70;
   3    420   6, 20, 28, 70;
   4    560   20, 28, 70;
   5    700   20, 28, 70;
   6    840   6, 20, 28, 70;
   7    980   20, 28, 70;
   8   1120   20, 28, 70;
   9   1144   88, 104, 572;
  10   1260   6, 20, 28, 70;
  11   1320   6, 20, 88;
  12   1400   20, 28, 70;
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000
• David A. Corneth, PARI program

Crossrefs

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

Subsequence of: A337688.

Programs

PARI

See Corneth link \\ David A. Corneth, Oct 07 2020

Formula

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