A195212 Numbers n for which the exponent of the largest prime factor of n is even.

4, 9, 16, 18, 25, 36, 49, 50, 64, 72, 75, 81, 98, 100, 121, 144, 147, 150, 162, 169, 196, 200, 225, 242, 245, 256, 288, 289, 294, 300, 324, 338, 361, 363, 392, 400, 441, 450, 484, 490, 507, 529, 576, 578, 588, 600, 605, 625, 648, 675, 676, 722, 726, 729, 735

Offset: 1

Author

Charles R Greathouse IV, Sep 13 2011

Keywords

• nonn

Comments

What is the density of these numbers? It's clear that lim a(n)/n^2 = 0.

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Contains the squares, A000290, as a subsequence (apart from 0 and 1).

Programs

Mathematica

Select[Range[800],EvenQ[FactorInteger[#][[-1,2]]]&] (* Harvey P. Dale, Jul 22 2013 *)

PARI

is(n)=if(n<4,0,n=factor(n)[,2];n[#n]%2==0) \\ Charles R Greathouse IV, Sep 14 2011