@article{JIS_2010__13_2_a3,
     author = {Chappelon, Jonathan},
     title = {On the multiplicative order of $a^n$ modulo $n$},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {2010},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2010__13_2_a3/}
}