更新1:
Btw triangle number means something that can be expressed as 1+2+3+4...
Btw triangle number means something that can be expressed as 1+2+3+4...
收錄日期: 2021-05-01 20:56:52
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20171207034823AAJR2hU