L_i=1+\sum_{k=1}^i\varphi(k)
$$
-**本页面主要译自博文[Дерево Штерна-Броко. Ряд Фарея](http://e-maxx.ru/algo/stern_brocot_farey)与其英文翻译版[The Stern-Brocot Tree and Farey Sequences](https://cp-algorithms.com/others/stern_brocot_tree_farey_sequences.html)。其中俄文版版权协议为 Public Domain + Leave a Link;英文版版权协议为 CC-BY-SA 4.0。**
+ **本页面主要译自博文[Дерево Штерна-Броко. Ряд Фарея](http://e-maxx.ru/algo/stern_brocot_farey)与其英文翻译版[The Stern-Brocot Tree and Farey Sequences](https://cp-algorithms.com/others/stern_brocot_tree_farey_sequences.html)。其中俄文版版权协议为 Public Domain + Leave a Link;英文版版权协议为 CC-BY-SA 4.0。**