61188domain: NAppears in sequencesNumber of 2 X 2 matrices having all terms in {-n,...,0,..,n} and positive even determinant.at n=9A211157Number of nX5 0..1 arrays with every element equal to 0, 2, 3, 5 or 6 king-move adjacent elements, with upper left element zero.at n=7A298379