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Math Help - what is the radius of convergence of the power series Σan xⁿ

  1. #1
    Junior Member sorv1986's Avatar
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    Cool what is the radius of convergence of the power series Σan xⁿ

    suppose Σan xⁿ be a power series and an= the number of divisors of n⁵⁰.

    Then what will be the radius of convergence of this power series?

    Thanks in advance . regards.
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  2. #2
    MHF Contributor FernandoRevilla's Avatar
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    Re: what is the radius of convergence of the power series Σan xⁿ

    Quote Originally Posted by sorv1986 View Post
    suppose Σan xⁿ be a power series and an= the number of divisors of n⁵⁰. Then what will be the radius of convergence of this power series?
    Hint 1\leq a_n\leq n^{50}\Rightarrow 1\leq a_n^{1/n}\leq (n^{1/n})^{50} . Now, apply the Sandwich Theorem.
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