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 A091192 Abundant numbers having at least one abundant proper divisor. 4
 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

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Last modified July 23 22:20 EDT 2021. Contains 346265 sequences. (Running on oeis4.)