Figure 6: Four groups of sixteen 2D maps in the range of n=15, k={2,3,4,7}, N ≅ 200 ~ 600, T=200 ~ 600, T=2700 ; (a) group (a1-a4) four MapA maps; (b) group (b1-b4) four MapT maps; (c) (c1-c4) four MapG maps; (d) (d1-d4) four MapC maps for the file 201-500.