The first factorization discovered (and "proved") in James Sellers' paper Domino Tilings and Products of Fibonacci and Pell Numbers published in Journal of Integer Sequences, Vol. 5 (2002), Article 02.\ 1.2, is: [[1, 2], [1, 1]], [[2, 5], [2, 1]] The second factorization discovered (and "proved") in that paper is: [[1, 2], [3, -1]], [[1, 4], [5, -1]] The third factorization discovered (and whose "proof" was left to the reader\ , since it was too "complicated") in that paper is: [[1, 1], [1, 1]], [ [1, 1, 17, 51, 449, 1853, 12853, 61557], [1, 25, 11, -47, -11, 25, -1, -1]] This took, 0.487, seconds .