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本書可以伸出桌子邊緣多遠而不會倒塌？結果表明，
本書的最大可能懸垂距離 
（以書長為單位）是 調和級數的第 
個部分和的一半。
是一個 調和數。 前幾個值是
個書長的懸垂距離所需的堆疊書本數量，求解關於 
的 
方程，並取 上限函式。對於 
, 2, ... 個書長的懸垂距離，需要 4, 31, 227, 1674, 12367, 91380, 675214, 4989191, 36865412, 272400600, ... 本書 (OEIS A014537)。