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Math Help - annulus of convergence

  1. #1
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    annulus of convergence

    calculate the annulus of convergence of \Sigma _{j=-\infty, j \neq 0} ^\infty z^j / j^j
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  2. #2
    MHF Contributor chisigma's Avatar
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    The critical point is relative to the sum of the powers of z with negative exponent...

    \sum_{j=1}^{\infty} \frac{(-j)^{j}}{z^{j}} (1)

    In fact the (1) diverges for any value of z\ne 0...

    Kind regards

    \chi \sigma
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