OFFSET
1,1
MATHEMATICA
perfectQ[n_] := DivisorSigma[1, n] == 2*n; Select[Range[10000], perfectQ[DivisorSigma[1, #] / DivisorSigma[0, #]] &] (* T. D. Noe, Nov 13 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zdenek Cervenka, Nov 13 2012
EXTENSIONS
a(21)-a(32) from Donovan Johnson, Nov 13 2012
STATUS
approved