If you would have
Domain-A-.com redirecting to Domain-B-.com then Domain-B-.com will be indexed.
Code "301" is interpreted as "moved permanently".
The page that does the 301 redirect will maintain indexed but will gradually transfer it's authority to the new page the 301 redirects to.
If the page wasn't indexed in the first place i don't suspect it to be indexed as it redirects to another page and that particular page will be evaluated and indexed.
Eventually the 301 redirect page will be dropped from the index and your new page will receive it's authority.
But you should always keep the 301 in place.