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PutnamSuperchallengeIntegrals I: Feynman's Trick

Integrals I: Feynman's Trick · Superchallenge problem

Let f(x)=x+1x−1f(x) = \dfrac{x+1}{x-1} for x≠1x \ne 1. Compute f2025(3)f^{2025}(3), where fnf^{n} denotes ff composed with itself nn times.