A284763 Numbers n such that A279513(n) is squarefree.

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

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