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

1,1

Links

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

Example

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A124626 A231547 A290141 * A342100 A153501 A215012

Adjacent sequences: A087242 A087243 A087244 * A087246 A087247 A087248

Keyword

nonn

Author

Labos Elemer, Sep 05 2003

Status

approved