71810domain: NAppears in sequencesa(n) = Sum_{i=0..n, j=0..n} A026648(i,j).at n=14A026657Number of (n+2) X (4+2) 0..3 arrays with every 3 X 3 subblock row and column sum not 2 3 6 or 7 and every diagonal and antidiagonal sum 2 3 6 or 7.at n=12A251890