Use SUMPRODUCT(ISBLANK()) to count alternated cells range

Hi, I’m trying to count the blank cells using the formula =SUMPRODUCT(ISBLANK()), but I realized that I can only count consecutive cells like =SUMPRODUCT(ISBLANK(V7:V21)) and what I need is to count alternated blank cells like (V7;V9;V11;V17;V19;V21).
Is it possible?

Did you thoroughly consider the tags?
If relying on tahs most users will mainly think of the application names. Thus this topic should first be tagged calc, then (probably) one or two additional tags.

Didn’t know that the tags order influenciate on how people find or understand the topic. But I’ll make sure to tag the software name as first one, not the last as I did. Thanks!

Sorry to say: Sheets where formulas have to reference every other row should be redesigned. An example where such a construct is good practice would be interesting to see.
To make provisional repairs you may use
Once again: That’s not a solution you should use again and again.

Thanks for your answer! I’ll try to reorganize it to make it work using =SUMPRODUCT(ISBLANK()).