How do we rearrange the terms of the harmonic series so they add up to 0

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The harmonic series converges conditionally; therefore, the series can be rearranged in any way to get different sums, but how do we rearrange in such a way that it equates to 0. Is there a trick/ formula I could use to manipulate the series to equate it to 0 or to any number?

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I let do the task by Mathematica, and obtained a surprise:

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We see here not a more or less random sequence of positive and negative terms, depending on arithmetic accidents, but a definite pattern: There are blocks of five subsequent terms of the following kind: $${1\over 2n-1}, -{1\over 8n-6}, \ -{1\over 8n-4}, \ -{1\over 8n-2}, \ -{1\over 8n} \qquad(n\geq1)\ .$$ I hope that someone will be able to prove that the sequence will go on forever like that.