204716domain: NAppears in sequences(1+7*x-6*x^2)/(1-4*x-8*x^2+6*x^3).at n=7A177370Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000001 00000011 or 00001011.at n=12A260494a(n) = n! * (1 + Sum_{k=0..n} binomial(k+1,2) / k!).at n=8A368762