题目

Dr. K was one of my favorite professors in college. He was unique because he admitted telling lies in his21. I remembered the 22to his teaching at the beginning of his first class: “Now let me23 how I teach. Between today until the class right before finals, I’ll put a24into each of my lectures. Your job is to try and 25me in the Lie of the Day.”And thus 26our ten-week course. Early in the course, the Lie of the Day was usually obvious —27causing a forest of raised28 to challenge the lie. Dr. K would smile, saying, “Very good! In fact, the opposite is 29.” As the course prog下列是有规律排列的一列数：，， ，，，…，请观察此数列的，按此规律，第个数应是___________．