150510

Appears in sequences

• Number of (n+1) X (n+1) -7..7 symmetric matrices with every 2 X 2 subblock having sum zero and three distinct values.at n=12A211442
• Number of nX6 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.at n=9A280602