スターリング近似　はさみうち - SERP Analysis

https://stchopin.hatenablog.com/entry/2023/06/04/194708

https://examist.jp/mathematics/integration-expression/stirling/

https://note.com/suzukusa/n/na2a8dd28d484

http://sigmagic.net/math/stirling/

https://www.su-gaku.net/common/same/pdfjs/web/pdf/tokei-2.pdf

https://www.youtube.com/watch%3Fv%3DYsasW84wNro

https://wkmath.org/rec-int-f.html

https://qiita.com/yukkysaito/items/f9f8578eabf94fc67262

https://www.reddit.com/r/askmath/comments/1i8q0jx/limit_of_logxxlogx_as_x_approaches_infinity/%3Ftl%3Dja