@article{JIS_2016__19_7_a1,
     author = {Prodinger, Helmut},
     title = {Returns, hills, and $t$-ary trees},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {19},
     number = {7},
     year = {2016},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2016__19_7_a1/}
}