题干

观察下列一组数:﹣
1
4
3
9
,﹣ 16
5
25
7
,﹣ 36
9
,…,它们是按一定规律排列的,那么这一组数的第n个数是____
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答案(点此获取答案解析)

\uff08\ufe631\uff09n 2n\u22121(n+1

同类题3

根据下面短文内容,在短文的空格处填上一个恰当的词,使短文完整、通顺。

    A big company wanted to find someone to work for them. Lots of young college students came to ____ for the job, but only a small part of them were left. And this time, the company didn't plan to choose the right persons as usual.

    Here came the day when they took the final interview. A big box ____ of papers was placed on the way to the interview room, and a few papers were lying around the box.

    The first student came. He hurried along the way to take the interview. “Who put this ____ in the middle of the road?” the student said to himself, but he did not try to move the box away. Instead, he passed around the box and continued his way.

    The second student came along and did the same thing. Then another came, and another. All of them complained (抱怨) about the box but ____ of them tried to move it. What’s worse, someone even stepped (踩) on the papers and left without having a look at the things on the ground.

    Half an hour later, a thin young man with glasses came. He was also ____ those who were left to take the interview. He saw the box and the papers around it. Without thinking twice, he ____ and began to pick up the papers and put them into the box. Then he managed to move the box to the side. To his great ____, he found an invitation under the box. On it were the following words, “Congratulations, young man! You are the ____ person we are looking for! Would you like to join us?”

      Sometimes, you see, helping others is helping yourself.