Need help finding the frequency response
Is this for homework?

If so I won't directly give an answer, just a hint about the general approach that can be used to solve such questions without a single derivation:

Plot the impulse response. How does it look? Try building this by combining or modifying (through addition, dilatation, translation, multiplication, convolution, derivation, integration...) very simple functions the DFT of which is known (complex exponentials, constants, rectangles, diracs, Heaviside step). From then, use identities on the DFT to get the DFT of your impulse response.