(本小题满分12分)
设各项均为正数的数列

的前n项和为

,已知

,数列

是公差为

的等差数列。
(1)求数列

的通项公式(用

表示);
(2)设
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为实数,对满足

的任意正整数

,不等式
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都成立。求证:

的最大值为

。
解:(1)由题意知:
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,
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
,
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化简,得:
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
,
当

时,

,适合
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情形。
故所求

(2)

,

恒成立。
又

,

,
故
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,即

的最大值为

。
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
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
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
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
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
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
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

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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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

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
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
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
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
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
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
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
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