Red, yellow and blue are drawn side by side in four squares. How many different painting schemes are there?
1, there are three kinds of red, yellow and blue. 2. Choose two of the three colors as C 32 (that is, 3*2/2). Then fill up the two colors. A 52 (that is, five air plugs and two) 5*2. Complement each other 3, 3 color full row. A 53 (that is, five air plugs and three) 5*3*2. These three colors add up to 63.