Thank you guys, very helpful.

@Carl Love Thank you very much.

@nm Not at the same time. What I meant was if the function is f(x)+f(y), the output would be

f(1)+f(4)

f(7)+f(5)

@Carl Love  Thank you for the solution. But in my program, I didn't want the cartesian product. I have fixed values for (x2,x3,x4,x5). In my problem, there will be only 20 outputs. In particular, I want to calculate f(k,4,7,8,0),f(k,1,7,6,9),f(k,0,1,3,5),f(k,2,5,6,1) for k=1 to 5, without having to write each of these individually. Perhaps I should have been more careful in explaining my problem.

In addition, I donot want to actually calculate f at that point. I wish to keep f as it is such as the first two lines of the output would be:

2^1*(7^4+443^7+547^8+32^0)

2^1*(7^1+443^7+547^6+32^9)