摘要: Ugly numbers are numbers whose only prime factors are $2, 3$ $\mbox {or}$ $5$. The sequence $1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, \cdots$ shows the fir 阅读全文
posted @ 2020-07-29 23:50 Lcyanstars 阅读(207) 评论(1) 推荐(0) 编辑