332457domain: NAppears in sequencesNumber of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor.at n=14A206336G.f. A(x) satisfies: A(x) = x*exp(A(-x) - A(-x^2)/2 + A(-x^3)/3 - A(-x^4)/4 + ...).at n=33A307366