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A091192 Abundant numbers having at least one abundant proper divisor. 3
24, 36, 40, 48, 54, 60, 72, 80, 84, 90, 96, 100, 108, 112, 120, 126, 132, 140, 144, 150, 156, 160, 162, 168, 176, 180, 192, 198, 200, 204, 208, 210, 216, 220, 224, 228, 234, 240, 252, 260, 264, 270, 276, 280, 288, 294, 300, 306, 312, 320, 324, 330, 336, 340 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A080224(a(n))>1.

LINKS

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

Eric Weisstein's World of Mathematics, Abundant Number

EXAMPLE

24 is in the sequence since it is abundant, and 12 is a divisor of 24 which is also abundant.

MATHEMATICA

aQ[n_] := Module[{d = Divisors[n]}, Total@d > 2 n && AnyTrue[d[[2 ;; -2]], DivisorSigma[1, #] > 2# &]]; Select[Range[340], aQ] (* Amiram Eldar, Jun 21 2019 *)

PROG

(PARI) isabund(n) = sigma(n) > 2*n;

isok(n) = {if (isabund(n), fordiv(n, d, if ((d<n) && isabund(d), return(1)); ); ); return (0); } \\ Michel Marcus, Jun 21 2019

CROSSREFS

Cf. A005101, A080224, A091191.

Sequence in context: A102505 A112064 A090440 * A067807 A224907 A292352

Adjacent sequences:  A091189 A091190 A091191 * A091193 A091194 A091195

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Dec 27 2003

STATUS

approved

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Last modified May 29 06:31 EDT 2020. Contains 334697 sequences. (Running on oeis4.)