2001 AIME II Problems/Problem 3

Problem

Given that

$\begin{eqnarray*}x_{1}&=&211,\\ x_{2}&=&375,\\ x_{3}&=&420,\\ x_{4}&=&523, \textrm{ and}\\ x_{n}&=&x_{n-1}-x_{n-2}+x_{n-3}-x_{n-4}\textrm{ when }n\geq5, \end{eqnarray*}$ (Error compiling LaTeX. Unknown error_msg)

find the value of .

Solution

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