Excel 2007 : RAND formula

Hello Forum,

I'm new here and not overly familiar with the lingo, so pardon any confusing language. Basically, I'm trying to develop a random number generator for a fantasy football league. We have 3 divisions of 4 teams (12 overall) and there will need to be 13 weeks in which these teams will be playing one another. The first three weeks and last three weeks are all interdivisional so that there are actually only 7 weeks for which this formula will need to generate game matchups. Within these 7 weeks, divisional opponents cannot play each other. What I am seeking help on: developing a formula that creates pairs of the numbers 1-4 in a given week (i.e. both cells that generate a "3" would play each other that week) and that ensures two teams will not play each other more than once within that 7-week span.

I've used the random number TRUNC (RAND) function in the cells in this worksheet, but that doesn't ensure that only two of the same number are generated within a given week, nor that the same two teams will not be paired up in multiple weeks.

Sorry if this question seems trivial, but I'm sure I could also apply this further down the road in my professional work as well. And this might just be a fun exercise for someone one here to contemplate and help me solve.

Thank you in advance for the help and advice.

To help a little, let me point you at the RANDBETWEEN function rather than TRUNC(RAND). RANDBETWEEN does exactly what it sounds like it should - RANDBETWEEN (1, 10) will give you a random integer between 1 and 10. It comes with the same caveat as RAND, though - the value will be re-generated every time the spreadsheet is changed.

Other than that, well, coming up with Fantasy Spreadsheets has in the past been a 'specialist' area of mine, so maybe I can come up with something.

Oh - and you're just across the river from me!!