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  ______     ___                _____     ______  
 /_____//   / _ \\    ____     |  ___||  /_____// 
 `____ `   / //\ \\  |    \\   | ||__    `____ `  
 /___//   |  ___  || | [] ||   | ||__    /___//   
 `__ `    |_||  |_|| |  __//   |_____||  `__ `    
 /_//     `-`   `-`  |_|`-`    `-----`   /_//     
 `-`                 `-`                 `-`

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發送短信 : Ramanujan's series for 1/π: A survey