sum of products的用法和樣例：
例句
- In this paper,summation formulas of products involving odd-even index chebyshev polynomials of the second are given by using primary methods.
利用初等方法給出了一類包含奇下標第二類契貝謝夫多項式乘積和與一類包含偶下標第二類契貝謝夫多項式乘積和的求和公式。 - In this peper necessary and sufficient conditions for the semidirect products and wreath products of two scmigroup are given.
給出了兩個半群的半直積和圈積為左群的充分必要條件以及半直積的結構。
