In Dragon Ball Z, we are well acquainted with Androids 16, 17, and 18. In addition, we met Androids 19 and 20 (Dr. Gero) before 16-18. There may have been mention of others, but they were not developed or mentioned much to the extent of my memory.
I also think that we were introduced to Android 8 in Dragon Ball (the episode where Goku is ascending up the Muscle Tower with a new foe on each floor, one of which was Ninja Murasaki who on finding himself outmatched, ordered Android 8 to fight Goku, if I remember correctly).
However, I do not remember any mention of Androids 1-7, 9-15, and 21+, if they exist. Do they exist? Do we ever find out or know what happened to them? Is it further discussed in the manga?