This question is related to notation of infinite product.
We know that, $$ \prod_{i=1}^{\infty}x_{i}=x_{1}x_{2}x_{3}\cdots $$
How do I denote $$ \cdots x_{3}x_{2}x_{1} ? $$
One approach could be $$ \prod_{i=\infty}^{1}x_{i}=\cdots x_{3}x_{2}x_{1} $$
I need to use this expression in a bigger expression so I need a good notation for this. Thank you in advance for your help.