In my case the move-right button is ;
I want Ctrl; to move the cursor 7 characters to the right. I've tried the below .vimrc mapping, but it doesn't work:
nmap <c-;> 7;
Answer
Like previous comment says, it seems that ";" cannot be in the form <C-;>.
You can test typing Ctrl+V + key sequence.
Ctrl+V + ; gives only ; whereas Ctrl+V + L give ^L.
So I suppose that vim cannot recognize <C-;>.
You have some more information on the key codes help pages:
:help keycodes
:help <C-