关于e,π,i,1的2个如诗般恒等式（第1个是欧拉恒等式；第2个是高斯积分，可能很少有人注意到） 。我偶然在实分析及其在经济学中的应用（Real Analysis with Economic Applications ）这本书里面看到的。

... mathematics is very much like poetry ... what makes a good poem - a great poem - is that there is a large  amount  of thought expressed in very few words.  In this sense formulas like are poems.

                                                                                                                                                       --Lipman Bers

As Martin Barlow put it once, mathematics attracts us because the need to memorize is minimal. So, only the more fundamental facts are labeled as theorems; they are worth memorizing. Most other results are put as propositions, comments, or exercises. Also put as exercises are results that can be understood only by doing the tedious work necessary. I believe in the Chinese proverb: I hear, I forget; I see, I remember; I do, I know.

                                                                                                                                                      --Erhan Cinlar

这些式子的详细介绍和推广见

欧拉公式https://zh.wikipedia.org/wiki/欧拉公式

高斯积分https://en.m.wikipedia.org/wiki/Gaussian_integral