A102750 Numbers n such that square of largest prime dividing n does not divide n.

2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 80, 82, 83, 84, 85

Offset

1,1

Comments

Numbers n such that the exponent of the largest prime dividing n is one. - Harvey P. Dale, May 02 2019

From Peter Munn, Sep 30 2020: (Start)

2 together with numbers on the left half of the Doudna sequence tree depicted in Antti Karttunen's 2014 comment in A005940.

This sequence and A335738, considered as sets, are related by the self-inverse function A225546(.), which maps the members of either set 1:1 onto the other set.

(End)

Links

Rémy Sigrist, Table of n, a(n) for n = 1..25000

Example

63 is included because 63 = 3^2 *7 and 7 (the largest prime dividing 63) only divides 63 once.

Mathematica

Select[Range[2, 100], FactorInteger[#][[-1, 2]]==1&] (* Harvey P. Dale, May 02 2019 *)

Prog

(PARI) isok(n) = my(f = factor(n)); n % f[#f~, 1]^2; \\ Michel Marcus, May 20 2014

Crossrefs

Cf. A070003 (complement, apart from the term 1 that is in neither sequence).

Related to A335738 via A225546.

Cf. A005940.

Sequence in context: A348964 A349026 A336360 * A349810 A317092 A349019

Adjacent sequences: A102747 A102748 A102749 * A102751 A102752 A102753

Keyword

nonn

Author

Leroy Quet, Feb 09 2005

Extensions

More terms from Erich Friedman, Aug 08 2005

Status

approved