838696domain: NAppears in sequencesNumber of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 or 01010101.at n=18A259736Determinant of the n X n matrix [(i-j)^2 + d(i,j)]_{1<=i,j<=n}, where d(i,j) is 1 or 0 according as i = j or not.at n=9A355175