400028domain: NAppears in sequencesa(n) is the binary XOR of all n-bit squares, with a(2)=0 indicating that no 2-bit squares exist.at n=18A298816Number of nX5 0..1 arrays with every element equal to 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=7A300462