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 _____     _    _    _    _      ___      _____   
|  __ \\  | || | || | \  / ||   / _ \\   |__  //  
| |  \ || | || | || |  \/  ||  / //\ \\    / //   
| |__/ || | \\_/ || | .  . || |  ___  ||  / //__  
|_____//   \____//  |_|\/|_|| |_||  |_|| /_____|| 
 -----`     `---`   `-`  `-`  `-`   `-`  `-----`

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Text this: A combinatorial identity with application to estimation