Sorry, you are right, I did miss that one 4c4. I still think the link is usefull. It clearly illustrates the pattern. It would be farly simple to program I think. if you had 4 elemts say a,b,c, and d. then you would start with the first one A and go B,C,D, then increment a counter and start with the second one B and add C and D then the last one woud be CD. that would be taking them two at a time, then do it three at a time then the last time is four at a time, then so on.. you would need some do loops or FOR loops,… seems fairly straight forward. Wish I had time to program it, sounds like an intresting exercise in using loops.