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%I #18 Nov 14 2012 03:02:55
%S 7,21,25,29,246,286,2688,4062,33550337,4294934526,5658405646,
%T 5726153206,5726306566,6987790105,7533178601
%N Numbers n such that sigma(n) - tau(n) is a perfect number.
%F Numbers n such that sigma(n) - tau(n) is a perfect number.
%t perfectQ[n_] := DivisorSigma[1, n] == 2*n; Select[Range[100000], perfectQ[DivisorSigma[1, #] - DivisorSigma[0, #]] &] (* _T. D. Noe_, Nov 13 2012 *)
%Y Cf. A000396 (perfect numbers).
%K nonn
%O 1,1
%A _Zdenek Cervenka_, Nov 13 2012
%E 25 and 29 added by _T. D. Noe_, Nov 13 2012
%E a(10)-a(15) from _Donovan Johnson_, Nov 13 2012
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