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 A284763 Numbers n such that A279513(n) is squarefree. 2
 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, 34, 35, 37, 38, 39, 40, 41, 42, 43, 45, 46, 47, 49, 51, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 82, 83, 85, 86, 87, 88, 89 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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). This sequence contains the squarefree numbers (A005117); 8 = 2^3 is the first term in this sequence that is not squarefree. All terms belong to A144146; 81 = 3^2^2 is the first term of A144146 that is not in this sequence. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 EXAMPLE 8 = 2^3 belongs to this sequence. 24 = 3*2^3 does not belong to this sequence. PROG (PARI) a279513(n) =  my (f=factor(n)); prod(i=1, #f~, f[i, 1]*a279513(f[i, 2])); isok(n) = issquarefree(a279513(n)); \\ Michel Marcus, Apr 08 2017 CROSSREFS Cf. A005117, A144146, A182318. Sequence in context: A256450 A119605 A144146 * A090240 A137407 A261406 Adjacent sequences:  A284760 A284761 A284762 * A284764 A284765 A284766 KEYWORD nonn AUTHOR Rémy Sigrist, Apr 02 2017 STATUS approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)