Finding location in rand()

Given a large enough set of numbers is it possible to determine the seed and location in the rand() function found in <cstdlib> and seeded using srand?

I know I can find the seed given the first few numbers (maybe there is a possibility of duplicates but I haven't had that problem) but what if the numbers are located after rand() has been called numerous times.

If anyone can give me the formula used to calculate the rand() function I might be able to solve this problem.

Any help would be appreciated.
Thanks

Is it possible? Sure.

As for the formula that would be implamentation defined.