a notorious functional equation.
This problem is everywhere!
Finding the nontrivial zeros of the Riemann Zeta Function using Desmos
A deceivingly difficult differential equation.
Innocent looking, but ????
Matrix exponentials, determinants, and Lie algebras.
An equation Diophantus never considered.
i-th root of -1
a nice functional equation.
Integrating the impossible
A Curious Functional Equation | Math Olympiads
Terry Tao, Ph.D. Small and Large Gaps Between the Primes