I remember this from way back in grade school, but have forgotten the name. Here’s what I’m trying to describe.
In the song “25 or 6 to 4” by Chicago there is a bass (?) line that keeps the following beat: 12345, 12345, 12345, 1234-1234, dropping as it goes along, then repeat. This is kept up through much of the song. It’s a fairly complex, repeating, beat.
This type of musical construct has a name but for the life of me I can’t remember what it is called.