@article{JIS_2004__7_3_a3,
     author = {Lamathe, C\'edric},
     title = {The number of labelled $k$-arch graphs},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {7},
     number = {3},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2004__7_3_a3/}
}