188382domain: NAppears in sequencesNumber of (n+2)X(2+2) 0..3 arrays with every 3X3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3X3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.at n=10A252517Product_{n>=1} (1 + a(n)*x^n) = 1 + x + x^2 + 2 * Sum_{n>=3} a(n)*x^n.at n=18A348756