It is not necessary to care about the total energy versus the number of k points in irreducible reciprocal space, which is closely related to the symmetry of the investigated structure. Of course, you can always read it from
IBZKPT with a self-consistent run or any other run using VASP. Also, the printed number in
IBZKPT is related to the
I assume what you really care about is the total energy versus k-sampling. About the convergence tests with VASP, namely total energy versus cut-off energy and also versus k-sampling, I strongly suggest you to take a look at this tutorial: https://dannyvanpoucke.be/vasp-tutor-convergence-testing-en/
Hope it helps.