How to calculate poisson approximation?

[Emily Jenne]

I have a p-value definition as follows and I would like to implement it.

However, I am not sure how to programmatically write the possion approximation (as it goes upto infinity).

The values of n1, n2, n3, n4, n5 and N are as follows.

n1 = 102
n2 = 95

Calculating λ:

n3 = 1350
n4 = 3588
n5 = 886
N = 10382

So my λ would be 421.41

I followed scipy.stats.poisson documentation: https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.poisson.html

from scipy.stats import poisson
poisson.pmf(x, mu)

However, as I understand the calculation happens at 1 point. Therefore, I am not sure how to adapt it into my scenario. i.e. calculating from i = n1+n2, ..., ∞. (please bear with me as my understanding of statistics is very low). I would really appreciate any help in this regard.

I am happy to provide more details if needed.

Thank you.

-Emi