Filippo Disanto Andrea Frosini Renzo Pinzani Simone Rinaldi A Closed Formula for the Number of Convex Permutominoes. 2007 14 Electr. J. Comb. 1 http://www.combinatorics.org/Volume_14/Abstracts/v14i1r57.html db/journals/combinatorics/combinatorics14.html#DisantoFPR07