Hello Brian,
thanks for the infos - that makes something clear for me. It is similar to James patterns in this post: http://moi3d.com/forum/index.php?webtag=MOI&msg=7777.577
You may have a look to the shift-dublicate node - maybe it can help you - the difference to the progression node in arithmetic mode is that the input can take an array and shifts all values.

Have a nice day
Karsten