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A119433 Primitive elements of A119432. 4

%I

%S 2,105,165,195,3003,3927,4389,4641,4845,5187,5313,5865,6555,7395,7905,

%T 8265,8835,9435,10005,10455,10545,10695,10965,11685,11985,12255,12765,

%U 13395,13485,13515,14145,14835,15045,15105,15555,16215,16815,17085

%N Primitive elements of A119432.

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

%C 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

%H Charles R Greathouse IV, <a href="/A119433/b119433.txt">Table of n, a(n) for n = 1..10000</a>

%F 2 followed by odd elements of A119431.

%e From _Peter Munn_, Oct 23 2020: (Start)

%e Initial terms, showing factorization:

%e n a(n)

%e 1 2 = 2

%e 2 105 = 3 * 5 * 7

%e 3 165 = 3 * 5 * 11

%e 4 195 = 3 * 5 * 13

%e 5 3003 = 3 * 7 * 11 * 13

%e 6 3927 = 3 * 7 * 11 * 17

%e 7 4389 = 3 * 7 * 11 * 19

%e 8 4641 = 3 * 7 * 13 * 17

%e 9 4845 = 3 * 5 * 17 * 19

%e 10 5187 = 3 * 7 * 13 * 19

%e 11 5313 = 3 * 7 * 11 * 23

%e 12 5865 = 3 * 5 * 17 * 23

%e 13 6555 = 3 * 5 * 19 * 23

%e 14 7395 = 3 * 5 * 17 * 29

%e 15 7905 = 3 * 5 * 17 * 31

%e (End)

%t 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 *)

%Y Subsequence of A005117, A119432.

%Y Cf. A103288.

%K nonn

%O 1,1

%A _Franklin T. Adams-Watters_, May 19 2006

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Last modified June 17 13:12 EDT 2021. Contains 345080 sequences. (Running on oeis4.)