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%I #18 Apr 08 2017 09:51:30
%S 1,2,3,5,6,7,8,9,10,11,13,14,15,17,19,21,22,23,25,26,29,30,31,32,33,
%T 34,35,37,38,39,40,41,42,43,45,46,47,49,51,53,55,56,57,58,59,61,62,63,
%U 65,66,67,69,70,71,73,74,75,77,78,79,82,83,85,86,87,88,89
%N Numbers n such that A279513(n) is squarefree.
%C Also numbers with no duplicate prime number in their prime tower factorization (see A182318 for the definition of the prime tower factorization of a number).
%C This sequence contains the squarefree numbers (A005117); 8 = 2^3 is the first term in this sequence that is not squarefree.
%C All terms belong to A144146; 81 = 3^2^2 is the first term of A144146 that is not in this sequence.
%H Rémy Sigrist, <a href="/A284763/b284763.txt">Table of n, a(n) for n = 1..10000</a>
%e 8 = 2^3 belongs to this sequence.
%e 24 = 3*2^3 does not belong to this sequence.
%o (PARI) a279513(n) = my (f=factor(n)); prod(i=1, #f~, f[i, 1]*a279513(f[i, 2]));
%o isok(n) = issquarefree(a279513(n)); \\ _Michel Marcus_, Apr 08 2017
%Y Cf. A005117, A144146, A182318.
%K nonn
%O 1,2
%A _Rémy Sigrist_, Apr 02 2017
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