Riemann zeta function
Mathematicians are interested in those values of  for which the function is equal to zero. The Riemann hypothesis conjectures that all the "non-trivial zeros" lie on the critical line , meaning they are guessed to be of the form  for some real value t. It is already known that all of the non-trivial zeroes must lie in a region called the "critical strip" for which . So far, all of the computed nontrivial zeros are on the critical line.