[分析] 一題級數

[kemowu (小展)]

          ∞
Let {a_n }    be a sequence of numbers in [0,1]. Prove that
          n=1

∞        1
Σ  ─────── is finite for almost all x in [0,1].
n=1   2       1/2
     n  |x-a_n|

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◆ From: 140.115.221.107
推 ppia        :該級數第n項在[0,1]上積分小於1/n^2 根據Beppo Levi
→ ppia        :lemma, 該級數幾乎處處收斂到一可積函數