I am interested in combined score in enrichr and I found that it is calculated from p-value and z-score.

In official Q&A, the z-scores are calculated from random input gene lists and lookup table contains the z-scores.

My questions are that:

1. The numbers of random input gene are the same or different? I wonder how much the random inputs are random. Why I asked this question is that I tried to calculate z-score based on binomial distribution which the N is fixed but I failed to reproduce the results.
2. How can I get z-score lookup table?

Thanks!