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A119433
Primitive elements of A119432.
4
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
KEYWORD
nonn
AUTHOR
STATUS
approved