MathCastle
Proof WritingHardInduction

Induction · Hard problem

With F1=F2=1F_1 = F_2 = 1 and Fn+1=Fn+Fn−1F_{n+1} = F_n + F_{n-1}, strong induction proves Fn≥(32)n−2F_n \ge \left(\tfrac32\right)^{n-2}. What is the smallest nn with Fn>1000F_n > 1000?