@article{10_4064_aa168_2_6,
     author = {Florian Luca and Carl Pomerance},
     title = {The range of the sum-of-proper-divisors function},
     journal = {Acta Arithmetica},
     pages = {187--199},
     publisher = {mathdoc},
     volume = {168},
     number = {2},
     year = {2015},
     doi = {10.4064/aa168-2-6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa168-2-6/}
}