@article{JIS_2005__8_2_a2,
     author = {Gessel, Ira M. and Xin, Guoce},
     title = {A combinatorial interpretation of the numbers $6(2n)!/n!(n+2)!$},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {8},
     number = {2},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2005__8_2_a2/}
}