@article{JIS_2010__13_3_a3,
     author = {Firoozbakht, Farideh and Hasler, Maximilian F.},
     title = {Variations on {Euclid's} formula for perfect numbers},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {13},
     number = {3},
     year = {2010},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2010__13_3_a3/}
}