you are right:C(20,4)=C(16+3,3)+C(15+3,3)+...+C(1+3,3)+C(0+3,3)

来源: 皆兄弟也于 2010-09-08 10:09:50 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

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