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Re:公式的推导

Posted by skogt at 2010-07-28 09:11:56 on Problem 2140
In Reply To:公式的推导 Posted by:Ly86 at 2010-04-25 19:03:36

> 假设a,a+1,a+2...a+k ，为一组符合的答案
> 有
> (k+1)a+0.5*k*(k＋1)=n成立
> 划成
> (a + 0.5*k)(k+1)=n
> 观察等式发现必须满足
> 1. 0.5*k为整数. 所以k是偶数
> 2. (k+1) 为n的因数，并且 (k+1) 为奇数
> 所以综上
> n有多少个奇因数，就是本题的答案

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Re:公式的推导 (49) skogt 2010-07-28 09:13:27

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