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PutnamSuperchallengeIntegrals I: Feynman's Trick

Integrals I: Feynman's Trick · Superchallenge problem

Evaluate ∑n=1∞Fn3n\displaystyle\sum_{n=1}^{\infty} \frac{F_n}{3^n}, where FnF_n are the Fibonacci numbers (F1=F2=1F_1 = F_2 = 1).