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[数列] 求和

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student_qwh Posted 2017-12-2 12:27 |Read mode
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kuing Posted 2017-12-2 12:39
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敬畏数学 Posted 2017-12-2 13:59
Last edited by 敬畏数学 2017-12-2 15:49$a_k=\dfrac{1}{2^k-1}-\dfrac{1}{2^{k+1}-1}$
这个公式刚才指数在下面,终于在上面。

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