A069189 Numbers k such that A007913(k) < sqrt(k).

4, 8, 9, 12, 16, 18, 25, 27, 32, 36, 45, 48, 49, 50, 54, 63, 64, 72, 75, 80, 81, 96, 98, 100, 108, 112, 121, 125, 128, 144, 147, 150, 160, 162, 169, 175, 176, 180, 192, 196, 200, 208, 216, 224, 225, 240, 242, 243, 245, 250, 252, 256, 275, 288, 289, 294, 300, 320

Offset: 1

Author

Benoit Cloitre, Apr 10 2002

Keywords

• easy
• nonn

Comments

Equivalently, numbers k whose squarefree part, A007913(k), is smaller than their square part, A008833(k). - Peter Munn, Mar 26 2021

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Square Part.
• Eric Weisstein's World of Mathematics, Squarefree Part.

Crossrefs

Cf. A007913, A008833.

Subsequence of A048098.

A116882 is a near equivalent with respect to a number's odd part.

Programs

Mathematica

f[p_, e_] := If[OddQ[e], p, 1]; sqf[n_] := Times @@ (f @@@ FactorInteger[n]); Select[Range[320], sqf[#] < Sqrt[#] &] (* Amiram Eldar, Apr 02 2020 *)

PARI

for(n=1,200,if(core(n)