A247180 Numbers with nonrepeating smallest prime factor.

2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 26, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 50, 51, 53, 54, 55, 57, 58, 59, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 82, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95, 97, 98

Offset

1,1

Comments

Complement of the union of {1} and A283050. The asymptotic density of this sequence is 1 - A283071 = 0.6699019646... - Amiram Eldar, Dec 08 2020

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Formula

a(n) mod A088377(a(n)) > 0;

A067029(a(n)) = 1.

Mathematica

Select[Range[100], FactorInteger[#][[1, 2]]==1&] (* Harvey P. Dale, Jan 29 2020 *)

Prog

(Haskell)
a247180 n = a247180_list !! (n-1)
a247180_list = filter ((== 1) . a067029) [1..]
(PARI) isok(m) = (m>1) && (factor(m)[1, 2] == 1); \\ Michel Marcus, Dec 08 2020

Crossrefs

Cf. A020639, A088377, A067029, A283050, A283071.

Subsequences: A005117, A016825.

Sequence in context: A374038 A203076 A385098 * A375398 A317091 A048839

Adjacent sequences: A247177 A247178 A247179 * A247181 A247182 A247183

Keyword

nonn

Author

Reinhard Zumkeller, Nov 23 2014

Status

approved