What is this equation with zeta from a T-Shirt in a video? There's an equation on a T-shirt in the music video by Remy Zero for "Gramarye". There's not a completely clear shot of it, but it's something along the lines of: $$?^{???}(z) = \frac{n !}{2 \pi ?} \int_{C} \frac{f(\zeta)}{(\zeta - z)^{n+1}} d\zeta \,$$ Can anyone fill in the blanks and identify what that is? Searched around a bit on line integrals and zeta functions and didn't find anything !Gramarye T-shirt

Turning comment into an answer.

That is Cauchy's integral formula. The full formula is given by

$$f^{(n)}(z) = \frac{n !}{2 \pi i} \int_{C}\\! \frac{f(\zeta)}{(\zeta - z)^{n+1}} \mathrm{d}\zeta $$