Why are conditionally convergent series interesting? While mathematicians might
undoubtably give many answers to such a question, Riemann’s theorem on rearrangements of
Sum of the alternating harmonic series ∑ ∞ k=1 (−1) k+1 k =11 −12 +⋯
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10 I know that the harmonic series ∑ k=1 ∞ 1k =11 +12 +13 +14 +15 +16 +⋯+1n +⋯ (I) diverges, but what about the alternating harmonic series
∑ k=1 ∞ (−1) k+1 k =11 −12 +13 −14 +15 −16 +⋯+(−1) n+1 n +⋯? (II)
Does it converge? If so, what is its sum?