I have 10 resistors of 18 ohms/25 watts each. I will use them for a load bank I am building.

In trying to achieve flexibility, I began asking myself what maximum number of different resistances are possible with any combination of them. It is obvious that two in parallel is 9 ohms, three in parallel is

6 ohms, etc, down to 1.8 ohms. It is also obvious that two in series is 36 ohms, three is 54 ohms, etc up to 180 ohms.Then I began thinking of combinations of series/parallel like two in series (or parallel) with one in parallel (or series), and so on.

I think you get my drift. My brain too old and out of practice now to set up the problem and I was never good at that Binomial Theorem thing to begin with. Can somebody enlighten me?

Many thanks, John S