Notation for multi-sigma sum where index-values are never equal

Question

I'm wondering if the following:

$$\sum_{i_1=1}^n \biggr(\sum_{i_2=1}^{i_1-1} f(i_2) + \sum_{i_2=i_1+1}^n f(i_2)\biggr)$$

Can be abbreviated to this:

$$\sum_{i_1=1}^n \sum_{i_2=1, i_2\ne i_1}^n f(i_2) \tag1$$

I know this specific example could just be expressed as $\sum_{i=1}^n(n-1)f(i)$, but that isn't always going to the case for expressions with this index-inequality restriction. So, is $(1)$ acceptable notation?

Answer 1

Yes, it is clear.
I have also seen it as $$\sum_{i_1=1}^n\sum_{i_2=1\\i_2\ne i_1}^nf(i_2)$$