148364domain: NAppears in sequencesa(n) = (1/24)*(n+1)*(3*n^3+59*n^2+358*n+648).at n=29A090949Place n equally spaced points on each side of a square, and join each of these points by a chord to the 3*n new points on the other three sides: sequence gives number of regions in the resulting planar graph.at n=12A367278