每层阶梯上都趴着若干只青蛙,具体来说第 i 层阶梯上有 i 只青蛙。单身狗喷先生看到了这些青蛙,他想把前 x 层阶梯(含)上的所有青蛙两两凑成一对。很明显并不是所有的 x 都能满足这个条件,因为青蛙总数可能为奇数,此时一定有一只青蛙落单。
喷先生并不想看到有青蛙落单,所以他想让你回答一下,将 x 从小到大排序,第 n 个满足上述条件(即两两凑对不会出现落单青蛙)的 x 值应该是多少?
![](/upload/image/20240125/20240125204722_32837.png)
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)
一个整数 n ,表示第 n 个满足条件的 x 值。
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