A091192 - OEIS

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A091192

Abundant numbers having at least one abundant proper divisor.

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

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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: A112064 A090440 A376271 * A067807 A224907 A292352

Adjacent sequences: A091189 A091190 A091191 * A091193 A091194 A091195

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Dec 27 2003

STATUS

approved