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%I #22 Oct 18 2016 05:39:47
%S 1,56,60,96,132,184,204,248,276,348,376,480,492,504,564,568,612,632,
%T 636,672,708,824,852,864,996,1016,1056,1068,1208,1212,1248,1284,1336,
%U 1356,1520,1528,1572,1592,1632,1644,1656,1784,1788,1824,1908,1912,1980
%N Average divisor is an integer (A003601) and the number is refactorable (A033950).
%H Donovan Johnson, <a href="/A047727/b047727.txt">Table of n, a(n) for n = 1..10000</a>
%F Both sigma_1(x)/sigma_0(x) and x/sigma_0(x) are integers. - clarified by _Harvey P. Dale_, Apr 27 2012
%e x = 56, sigma(x) = 120, number of divisors of x = 8. 120/8 and 56/8 are integers.
%t adiQ[n_]:=Module[{ds1=DivisorSigma[1,n],ds0=DivisorSigma[0,n]} ,Divisible[ ds1,ds0]&&Divisible[n,ds0]]; Select[Range[2000],adiQ] (* _Harvey P. Dale_, Apr 27 2012 *)
%o (PARI) isok(n) = my(d = numdiv(n)); !(n % d) && !(sigma(n) % d); \\ _Michel Marcus_, Oct 15 2016
%Y Cf. A007691, A001599, A046985.
%K nonn
%O 1,2
%A _Labos Elemer_