Use yellow, red, green and pink beads to arrange in a string. The colors of any four adjacent beads are different. If you want the 27th one to be red, How can I wear it?

Use yellow, red, green and pink beads to arrange in a string. The colors of any four adjacent beads are different. If you want the 27th one to be red, How can I wear it?

Results: there were 6
1. After the current four are confirmed, the color of the nth from the 5th must be the same as that of the previous nth-4th
2. The 27th one is red, and the third one must be red. There are six different ways to wear 1, 2 and 4
It's easy to understand
Hope to help you!