The full name is Riemann Zeta Function. It's defined as:

One of its uses is as a comparison series for testing convergence however it is also related to the distribution of prime numbers and quantum systems energy levels. You can find
full discussion of Riemann Zeta Function in this website by Xavier Gourdon and Pascal Sebah, or in the books listed to the left.
Answered by:
Taylan Akdogan, Physics Grad Student, MIT, Cambridge

'A theory with mathematical beauty is more likely to be correct than an ugly one that fits some experimental data. God is a mathematician of a very high order, and He used very advanced mathematics in constructing the universe.'