53800domain: NAppears in sequencesNumber of (n+1) X 2 binary arrays with every 2 X 2 subblock commuting with each of its horizontal and vertical 2 X 2 subblock neighbors.at n=19A186454Sum_{i=1..n} Sum_{j=1..n} (i OR j), where OR is the binary logical OR operator.at n=40A258438