Perfect numbers and finite groups
Rendiconti del Seminario Matematico della Università di Padova, Tome 129 (2013), pp. 17-34 
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     author = {De Medts, Tom and Mar\'oti, Attila},
     title = {Perfect numbers and finite groups},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
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     year = {2013},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {129},
     mrnumber = {3090628},
     zbl = {1280.20026},
     language = {en},
     url = {https://www.numdam.org/item/RSMUP_2013__129__17_0/}
}
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De Medts, Tom; Maróti, Attila. Perfect numbers and finite groups. Rendiconti del Seminario Matematico della Università di Padova, Tome 129 (2013), pp. 17-34. https://www.numdam.org/item/RSMUP_2013__129__17_0/

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[2] T. De Medts, Recovering n from σ(n)/n , MathOverflow, http://mathoverflow.net/questions/56376.

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