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pow:problem6f21 [2021/11/22 23:20]
mazur
pow:problem6f21 [2021/11/23 12:52] (current)
mazur
Line 1: Line 1:
 +<box 85% round orange| Problem 6 (due Monday, November 22)>
  
 +Let $a_1=3/2$ and $a_{n+1}=a_n^2-a_n+1$. Compute the sum 
 +\[ \frac{1}{a_1}+\frac{1}{a_2}+\frac{1}{a_3}+\ldots .\]
 +
 +
 +
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 +
 +</​box>​
 +
 +Two solutions were received: from Ashton Keith and Pluto Wang. Both solvers show that if $a_1=a>​1$ then
 +the infinite sum is equal to 1/(a-1). Pluto'​s solution is essentially the same as our original solution.
 +Ashton'​s solution is based on the same idea, but used slightly differently,​ and some claims are not justified with sufficient rigor. For more details see the following link {{:​pow:​2021fproblem6.pdf|Solution}}.