531297domain: NAppears in sequencesa(n) = 3^n - n^2.at n=12A024025a(n) = 3^n - Fibonacci(n).at n=12A212323Number of (2+2)X(n+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=23A252386