My suggestion for you is to do that with
grep - an utility for UNIX-like systems that has been ported to Windows and can match lines using regular expressions.
grep is included with MinGW's MSYS package, the installer can be found here. (install only MSYS)
Then you'll have to add MSYS tools to your PATH variable, dafeult directory for MSYS is
Finally you can do your serach with this command:
ls -a | grep ^.+\..+\.r[0-9]+$
... which means: "get output from
ls -a (file listing including hidden files) and pass it to
grep, match lines that look like ..r[0-9]* (with at least one character symbolized by each asterisk)".