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A087245 Nonsquarefree abundant numbers. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 17 15:06 EDT 2021. Contains 343979 sequences. (Running on oeis4.)