A087245 Nonsquarefree abundant numbers.

12, 18, 20, 24, 36, 40, 48, 54, 56, 60, 72, 80, 84, 88, 90, 96, 100, 104, 108, 112, 120, 126, 132, 140, 144, 150, 156, 160, 162, 168, 176, 180, 192, 196, 198, 200, 204, 208, 216, 220, 224, 228, 234, 240, 252, 260, 264, 270, 272, 276, 280, 288, 294, 300, 304

Offset: 1

Author

Labos Elemer, Sep 05 2003

Keywords

• nonn

Examples

			m = 20 = 2*2*5 and sigma(20) = 42 > 2m = 40.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A087244-A087247, A008683, A000203, A013929, A005117, A005100, A005101.

Programs

Mathematica

aQ[n_] := !SquareFreeQ[n] && DivisorSigma[1, n] > 2n; Select[Range[300], aQ] (* Amiram Eldar, Sep 21 2019 *)

PARI

isok(n) = !issquarefree(n) && (sigma(n) > 2*n); \\ Michel Marcus, Sep 21 2019