HTML input pattern with lower key letters, numbers and a comma

Someone here who's familiar with html patterns? I need an input pattern rule that only allows strings like this:

"anke1,our4,tim2,test9"

• The input string only allows 3 or 4 lower key characters [a-z]{3,4}
• The numbers between 0 and 9 (but only one number) [0-9]{1}
• After each string there is a comma

• The string has no length restrictions.

  <form><input type="text" name"test" pattern="???"></form>

Maybe someone knows how to put all these rules together for an input pattern. Thanks in advance!