A119433 Primitive elements of A119432.

2, 105, 165, 195, 3003, 3927, 4389, 4641, 4845, 5187, 5313, 5865, 6555, 7395, 7905, 8265, 8835, 9435, 10005, 10455, 10545, 10695, 10965, 11685, 11985, 12255, 12765, 13395, 13485, 13515, 14145, 14835, 15045, 15105, 15555, 16215, 16815, 17085

Offset

1,1

Comments

Elements of A119432 that are not divisible by any smaller element of that sequence.

Appears to be the lexicographically latest sequence of squarefree numbers such that all numbers with abundance >= -1 (see A103288) are divisible by one of the terms. - Peter Munn, Oct 19 2020

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Formula

2 followed by odd elements of A119431.

Example

From Peter Munn, Oct 23 2020: (Start)
Initial terms, showing factorization:
   n   a(n)
   1      2 = 2
   2    105 = 3 * 5 * 7
   3    165 = 3 * 5 * 11
   4    195 = 3 * 5 * 13
   5   3003 = 3 * 7 * 11 * 13
   6   3927 = 3 * 7 * 11 * 17
   7   4389 = 3 * 7 * 11 * 19
   8   4641 = 3 * 7 * 13 * 17
   9   4845 = 3 * 5 * 17 * 19
  10   5187 = 3 * 7 * 13 * 19
  11   5313 = 3 * 7 * 11 * 23
  12   5865 = 3 * 5 * 17 * 23
  13   6555 = 3 * 5 * 19 * 23
  14   7395 = 3 * 5 * 17 * 29
  15   7905 = 3 * 5 * 17 * 31
(End)

Mathematica

Block[{a = {}}, Do[If[And[NoneTrue[a, Mod[i, #] == 0 &], 2 EulerPhi[i] <= i], AppendTo[a, i]], {i, 20000}]; a] (* Michael De Vlieger, Nov 05 2020 *)

Crossrefs

Subsequence of A005117, A119432.

Cf. A103288.

Sequence in context: A001184 A370963 A098653 * A307227 A042351 A258828

Adjacent sequences: A119430 A119431 A119432 * A119434 A119435 A119436

Keyword

nonn

Author

Franklin T. Adams-Watters, May 19 2006

Status

approved