162977domain: NAppears in sequencesNumber of (n+1) X (n+1) -5..5 symmetric matrices with every 2 X 2 subblock having sum zero and one or three distinct values.at n=12A211331Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000001 or 00000101.at n=13A259765